Intro statistics

Points Awarded

 90

Points Missed

 10

Percentage

 90%

1.

The histogram below shows the time visitors to a museum spent browsing an exhibit on a Saturday. There were 300 visitors that day. The following histogram is of the data collected.

Reference: Ref 1-3

The percent of visitors spending more than 85 minutes at the museum is closest to

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

2.

The following is a histogram showing the distribution of the average property damage caused by tornadoes per year over the period 1950 to 1999 in each of the 50 states and Puerto Rico. The data are in millions of dollars and the class intervals are “0 to < 10,” “10 to < 20,” and so forth.

Reference: Ref 1-6

The percent of the data with average property damage of under 20 million dollars is about

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

3.

A violin student records the number of hours she spends practicing during each of nine consecutive weeks.

Reference: Ref 2-1

What is the first quartile for this data?

Points Earned:

0/1

Correct Answer:

A

Your Response:

D

4.

A stemplot of ages of 18 faculty members in a college math department follows. 4|3 represents 43 years.

Reference: Ref 2-2

The first quartile of the age of the faculty members at Wilmington State is

Points Earned:

0/1

Correct Answer:

B

Your Response:

C

5.

The exam scores (out of 100 points) for all students taking an introductory Statistics course are used to construct the following boxplot.

Reference: Ref 2-3

Based on this boxplot, the interquartile range is closest to

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

6.

During the early part of the 1994 baseball season, many sports fans and baseball players noticed that the number of home runs seemed to be unusually large. Below are the team-by-team statistics on home runs hit from opening day through June 3 of the 1994 season. They are given as separate stemplots for the number of home runs by American and National League teams.

Reference: Ref 2-4

Which of the following is a correct statement?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

7.

A sample was taken of the salaries of 20 employees of a large company. The following is a boxplot of the salaries (in thousands of dollars) for this year.

Reference: Ref 2-5

Based on this boxplot, which of the following statements is true?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

8.

The five-number summary of a set of data

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

9.

The histogram below shows the average property damage in millions of dollars caused by tornadoes over a 50-year period in each of the states and Puerto Rico.

Reference: Ref 2-6

From the histogram, the first quartile must be

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

10.

The average salary of all female workers at a large plant is $35,000. The average salary of all male workers at the plant is $41,000. If there are more female workers than female workers at the plant, then the average salary at the plant must be

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

11.

The volume of oxygen consumed (in liters per minute) while a person is at rest and while he or she is exercising (running on a treadmill) was measured for each of 50 subjects. The goal is to determine if the volume of oxygen consumed during aerobic exercise can be estimated from the amount consumed at rest. The results are plotted below.

Reference: Ref 4-1

The scatterplot suggests

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

12.

A researcher states that bone density in women is negatively associated with age. This means that

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

13.

The form of the relationship in the following scatterplot might best be described as

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

14.

Which of the following statements is true?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

15.

The data in the scatterplot below are from a small data set. 

The data were classified as either being collected in the winter or in the summer. Those collected in the winter are indicated by open circles and those in the summer by solid circles. The overall correlation of the data in this scatterplot is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

16.

A locomotive's “adhesion” is the locomotive's pulling force as a multiple of its weight. This is an important performance measure of a locomotive. A diesel locomotive model has adhesion that varies in actual use according to a Normal distribution with mean 0.37 and standard deviation 0.04.

Reference: Ref 3-3

The first quartile for the adhesion distribution is

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

17.

The scores on the Wechsler Adult Intelligence Scale are approximately Normal with μ = 100 and σ = 15.

Reference: Ref 3-5

The proportion of adults with scores between 80 and 120 is closest to

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

18.

The scores on the Wechsler Adult Intelligence Scale are approximately Normal with μ = 100 and σ = 15.

Reference: Ref 3-5

The score needed to be among the highest 10% of all scores is closest to

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

19.

A company produces packets of soap powder labeled “Giant Size 32 Ounces.” The actual weight of soap powder in such a box has a Normal distribution with a mean of 33 oz and a standard deviation of 0.7 oz. To avoid having dissatisfied customers, the company says a box of soap is considered underweight if it weighs less than 32 oz. To avoid losing money, it labels the top 5% (the heaviest 5%) overweight.

Reference: Ref 3-6

How heavy does a box have to be for it to be labeled overweight?

Points Earned:

0/1

Correct Answer:

A

Your Response:

C

20.

A market research company employs a large number of typists to enter data into a computer database. The time taken for new typists to learn the computer system is known to have a Normal distribution with a mean of 130 minutes and a standard deviation of 20 minutes. A candidate is automatically hired if he or she learns the computer system in less than 100 minutes. A cut-off time is set at the slowest 40% of the learning distribution. Anyone slower than this cut-off time is not hired.

Reference: Ref 3-7

What proportion of candidates will be automatically hired?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

21.

In a study, nine tires of a particular brand were driven on a track under identical conditions. Each tire was driven a particular controlled distance (measured in thousands of miles), and afterward the tread depth was measured. Tread depth is measured in “mils.” Here, 1 mil is 0.001 inch. The least-squares regression line was computed, and added to a scatterplot of these data. On the plot, one data point is marked with an “X”.  The equation of the least-squares regression line is:

Also, r2 = 0.953.

Reference: Ref 5-1

We might feel comfortable using the least-squares regression equation to predict tread depth for a tire driven

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

22.

In a study, nine tires of a particular brand were driven on a track under identical conditions. Each tire was driven a particular controlled distance (measured in thousands of miles), and afterward the tread depth was measured. Tread depth is measured in “mils.” Here, 1 mil is 0.001 inch. The least-squares regression line was computed, and added to a scatterplot of these data. On the plot, one data point is marked with an “X”.  The equation of the least-squares regression line is:

Also, r2 = 0.953.

Reference: Ref 5-1

Which of the following statements is true?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

23.

In a study, nine tires of a particular brand were driven on a track under identical conditions. Each tire was driven a particular controlled distance (measured in thousands of miles), and afterward the tread depth was measured. Tread depth is measured in “mils.” Here, 1 mil is 0.001 inch. The least-squares regression line was computed, and added to a scatterplot of these data. On the plot, one data point is marked with an “X”.  The equation of the least-squares regression line is:

Also, r2 = 0.953.

Reference: Ref 5-1

Which of the following is true?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

24.

A researcher wants to determine whether the rate of water flow (in liters per second) over an experimental soil bed can be used to predict the amount of soil washed away (in kilograms). The researcher measures the amount of soil washed away for various flow rates, and from these data calculates the least-squares regression line to be amount of eroded soil = 0.4 + 1.3 × (flow rate) The correlation between amount of eroded soil and flow rate would be

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

25.

Suppose we fit the least-squares regression line to a set of data. Points with unusually large values of the residuals are called

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

26.

John's parents recorded his height at various ages up to 66 months. Below is a record of the results.

John's parents decide to use the least-squares regression line of John's height on age based on the data in the previous problem to predict his height at age 21 years (252 months). We conclude

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

27.

A study of elementary school children, ages 6 to 11, finds a high positive correlation between shoe size x and score y on a test of reading comprehension. The observed correlation is most likely due to

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

28.

According to the 2010 census, those states with an above average number X of people who fail to complete high school tend to have an above average number Y of infant deaths. In other words, there is a positive association between X and Y. The most plausible explanation for this association is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

29.

The following table describes the opinions of 570 people. Students were classified by class (freshman, sophomore, junior, or senior), and by their opinion of campus residence quality (high quality, medium quality, low quality).

Reference: Ref 6-2

What percent of all students that responded are sophomores?

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

30.

If X and Y are categorical variables, the best way to determine if there is a relation between them is to

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

31.

A researcher studying the effect of price cuts on consumers' expectations makes up two different histories of the store price of a hypothetical brand of laundry detergent for the past year. Eight students in a class view one or the other price history on a computer. Some students see a steady price, while others see regular sales that temporarily cut the price. Students are asked the price they would expect to pay.

Reference: Ref 9-2

The names of the eight subjects follow.

Use the following list of random digits: 41842 81868 71035 09001 43367 49497. Start at the beginning of this list and use single-digit labels to assign the first four subjects selected to have the steady price group, and the remaining four to the fluctuating price group. The subjects assigned to the fluctuating price group are

Points Earned:

0/1

Correct Answer:

D

Your Response:

B

32.

A researcher studying the effect of price cuts on consumers' expectations makes up two different histories of the store price of a hypothetical brand of laundry detergent for the past year. Eight students in a class view one or the other price history on a computer. Some students see a steady price, while others see regular sales that temporarily cut the price. Students are asked the price they would expect to pay.

Reference: Ref 9-2

The experimental units are

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

33.

In a study of human development, investigators showed two movies that were different types to groups of children. Crackers were available in a bowl, and the investigators compared the number of crackers eaten by children watching both movies. One movie was shown at 8 AM (right after the children had breakfast) and the other at 11 AM (right before the children had lunch). It was found that during the movie shown at 11 AM, more crackers were eaten than during the movie shown at 8 AM. The investigators concluded that the different types of movies had different effects on appetite.

Reference: Ref 9-3

The treatment in this experiment is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

34.

A study attempts to compare two sunscreens. Each of 50 subjects with varying skin complexions will use both sunscreens — Screen A on one side of his or her body and Screen B on the other side. For each subject, a coin is tossed in order to determine which side receives Screen A and which receives Screen B. Researchers measure the amount of ultraviolet light exposure over both treated areas for each subject. This is an example of

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

35.

Will a fluoride mouthwash used after brushing reduce cavities? Twenty sets of twins were used to investigate this question. One member of each set of twins used the mouthwash after each brushing, the other did not. After six months, the difference in the number of cavities of those using the mouthwash was compared with the number of those who did not use the mouthwash. This experiment uses

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

36.

A small math department has 6 faculty members and 30 students. It can send 6 people to a national convention and they would like to send 4 students and 2 faculty members. Of the 30 students, 4 are selected randomly, and then 2 faculty members are randomly selected from the six. This is an example of

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

37.

The Excite Poll is an online poll at poll.excite.com. You click on an answer to become part of the sample. One poll question was “Do you refer watching first-run movies at a movie theater, or waiting until they are available on home video or pay-per-view?” A total of 8896 people responded with 1118 saying they preferred theaters. From this survey you can conclude that

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

38.

At a large university a simple random sample of 5 female professors is selected and a simple random sample of 10 male professors is selected. The two samples are combined to give an overall sample of 15 professors. The overall sample is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

39.

A simple random sample of 1200 adult Americans is selected, and each person is asked the following question. “In light of the huge national deficit, should the government at this time spend additional money to establish a national system of health insurance?" Only 39% of those responding answered “Yes.” This survey

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

40.

A 1992 Roper poll found that 22% of Americans say that the Holocaust may not have happened. The actual question asked in the poll was  “Does it seem possible or impossible to you that the Nazi extermination of the Jews never happened?" and 22% responded “Possible.” The results of this poll cannot be trusted because

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

41.

In a survey of sleeping habits, 8400 national adults were selected randomly and contacted by telephone. Respondents were asked, “Typically, how many times per week do you sleep less than 6 hours during the night?” On average, those surveyed reported an average of 1.8 nights per week in which they got less than 6 hours of sleep.

Reference: Ref 11-1

Which of the following is true with respect to this scenario?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

42.

The variability of a statistic is described by

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

43.

Parts being manufactured at a plant are supposed to weigh 40 grams. Suppose the distribution of weights has a Normal distribution with mean 40 grams and standard deviation 2 grams. Quality control inspectors randomly select 16 parts, weigh each, and then compute the sample average weight for the 16 parts.

Reference: Ref 11-7

The sampling distribution of the sample mean

Points Earned:

0/1

Correct Answer:

A

Your Response:

B

44.

A manufacturing process produces bags of cookies. The distribution of content weights of these bags is Normal with mean 16.0 oz and standard deviation 0.8 oz. We will randomly select n bags of cookies and weigh the contents of each bag selected.

Reference: Ref 11-8

How many bags should be selected so that the standard deviation of the sample mean is 0.1 ounces?

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

45.

A North American roulette wheel has 38 slots, of which 18 are red, 18 are black, and 2 are green.

Reference: Ref 10-1

Suppose you decide to bet on red on each of 10 consecutive spins of the roulette wheel. Suppose you lose all 5 of the first wagers. Which of the following is true?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

46.

An assignment of probabilities to events in a sample space must obey which of the following?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

47.

Event A occurs with probability 0.2. Event B occurs with probability 0.3. Event C occurs with probability 0.4. If A, B, and C are disjoint, then

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

48.

At a small college, all entering freshmen must take a foreign language class, chosen from the languages Spanish, French, Swahili, Chinese, and Arabic. The probability distribution for the language studied by a randomly selected freshman is summarized in the following table:

Reference: Ref 10-4

The probability that the freshman is studying Chinese or Swahili is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

49.

I choose a card at random from a well-shuffled deck of 52 cards. There is a 1/4 probability that the card chosen is a spade, a 1/4 probability that the card is a heart, a 1/4 probability that the card is a diamond, and a 1/4 probability that the card is a club. Both spades and clubs are black cards, while hearts and diamonds are red.

Reference: Ref 10-5

The probability that the card chosen is not a spade is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

50.

The density curve for a continuous random variable X has which of the following properties?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

51.

A deck of cards is shuffled, and you choose one at random, observe its color, and replace it in the set. The cards are thoroughly reshuffled, and you again choose a card at random, observe its color, and replace it in the set. This process is repeated until you get a red card with X denoting the number of draws required. The random variable X has which of the following probability distributions?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

52.

In an instant lottery, your chances of winning are 0.1. If you play the lottery five times and outcomes are independent, the probability that you lose all five times is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

53.

A local politician claims that 1 in 5 automobile accidents involves a teenage driver. He is advocating increasing the age at which teenagers can drive alone. Over a 2-month period there are 67 accidents in your city, and only 9 of them involved a teenage driver. If the politician is correct, what is the chance that you would observe 9 or fewer accidents involving a teenage driver?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

54.

A roulette wheel has 38 slots in which the ball can land. Two of the slots are green, 18 are red, and 18 are black. The ball is equally likely to land in any slot. The roulette wheel is going to be spun twice and the outcomes of the two spins are independent.

Reference: Ref 12-1

The probability that it lands on red at least once is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

55.

A survey of college students finds that 20% like country music, 15% like gospel music, and 10% like both country music and gospel music.

Reference: Ref 12-2

The proportion of students that like neither country music nor gospel music is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

56.

A system has two components that operate in parallel, as shown in the following diagram. Because the components operate in parallel, at least one of the components must function properly if the system is to function properly. The probabilities of failures for the components 1 and 2 during one period of operation are 0.20 and 0.03, respectively. LetF denote the event that component 1 fails during one period of operation and G denote the event that component 2 fails during one period of operation. The component failures are independent. 

Reference: Ref 12-3

The probability that the system functions properly during one period of operation is closest to

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

57.

The following table gives the sex and age group of college students at a Midwestern university.

A student is to be selected at random.

Reference: Ref 12-5

The probability that the selected student is a female that is 15 to 17 years old is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

58.

The following table gives the sex and age group of college students at a Midwestern university.

A student is to be selected at random.

Reference: Ref 12-5

Given that the selected student is female, the conditional probability that he is 25 to 34 years old is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

59.

A stack of four cards contains two red cards and two black cards. I select two cards, one at a time, and do not replace the first card selected before selecting the second card. Consider the events     A = the first card selected is red.     B = the second card selected is red. The events A and B are

Points Earned:

0/1

Correct Answer:

D

Your Response:

C

60.

In a particular game, a fair die is tossed. If the number of spots showing is a six, you win $6, if the number of spots showing is a five, you win $3, if the number of spots showing is 4, you win $2, and if the number of spots showing is 3, you win $1. If the number of spots showing is 1 or 2, you win nothing. You are going to play the game twice.

Reference: Ref 12-6

The probability that you win something on each of the two plays of the game is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

61.

A medical researcher treats 400 subjects with high cholesterol with a new drug. The average decrease in cholesterol level is  = 90 after two months of taking the drug. Assume that the decrease in cholesterol after two months of taking the drug follows a Normal distribution, with unknown mean μ and standard deviation σ = 30.

Reference: Ref 14-1

A 95% confidence interval for μ is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

62.

You measure the lifetime of a random sample of 64 tires of a certain brand. The sample mean is  = 50 months. Suppose that the lifetimes for tires of this brand follow a normal distribution, with unknown mean μ and standard deviation σ = 5 kg.

Reference: Ref 14-2

A 99% confidence interval for μ is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

63.

You measure the lifetime of a random sample of 64 tires of a certain brand. The sample mean is  = 50 months. Suppose that the lifetimes for tires of this brand follow a normal distribution, with unknown mean μ and standard deviation σ = 5 kg.

Reference: Ref 14-2

Suppose I had measured the lifetimes of a random sample of 100 tires rather than 64. Which of the following statements is true?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

64.

To assess the accuracy of a laboratory scale, a standard weight known to weigh 1 gram is repeatedly weighed a total of n times, and the mean  of the weighings is computed. Suppose the scale readings are Normally distributed, with unknown mean m and standard deviation σ = 0.01 g. How large should n be, so that a 95% confidence interval for mhas a margin of error of ± 0.0001?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

65.

The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures the motivation, attitudes, and study habits of college students. Scores range from 0 to 200 and follow (approximately) a Normal distribution, with mean of 110 and standard deviation σ = 20. You suspect that incoming freshman have a mean μ, which is different from 110 because they are often excited yet anxious about entering college. To verify your suspicion, you test the hypotheses

H0: μ = 110, Ha: μ  110

You give the SSHA to 50 students who are incoming freshman and find their mean score.

Reference: Ref 15-1

If you observe a sample mean of = 115.35, what is the corresponding P-value?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

66.

A university administrator obtains a sample of the academic records of past and present scholarship athletes at the university. The administrator reports that no significant difference was found in the mean GPA (grade point average) for male and female scholarship athletes (P = 0.287). This means that

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

67.

Suppose we want a 90% confidence interval for the average amount of time (in minutes) spent per week on homework by the students in a large introductory statistics course at a large university. The interval is to have a margin of error of 3 minutes, and the amount spent has a Normal distribution with a standard deviation σ = 40 minutes. The number of observations required is closest to

Points Earned:

0/1

Correct Answer:

B

Your Response:

C

68.

Twenty-five seniors from a large metropolitan area school district volunteer to allow their Math SAT test scores to be used in a study. These 25 seniors had a mean Math SAT score of  = 450. Suppose we know that the standard deviation of the population of Math SAT scores for seniors in the district is σ = 100. Assuming the population of Math SAT scores for seniors in the district is approximately Normally distributed, a 90% confidence interval for the mean Math SAT score μ for the population of seniors computed from these data is

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

69.

You conduct a statistical test of hypotheses and find that the null hypothesis is statistically significant at level α = 0.05. You may conclude that

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

70.

A certain population follows a Normal distribution, with mean μ and standard deviation σ = 2.5. You collect data and test the hypotheses

H0: μ = 1, Ha: μ  1

You obtain a P-value of 0.072. Which of the following is true?

Points Earned:

0/1

Correct Answer:

A

Your Response:

C

71.

A researcher wishes to determine if the use of an herbal extract improves memory. Subjects will take the herbal extract regularly during a 10-week period of time. After this course of treatment, each subject has his or her memory tested using a standard memory test. Suppose the scores on this test of memory for all potential subjects taking the herbal extract follow a Normal distribution with mean μ and standard deviation σ = 6. Suppose also, that in the general population of all people, scores on the memory test follow a Normal distribution, with mean 50 and standard deviation σ = 4. The researcher, therefore, decides to test the hypotheses

H0: μ = 50, Ha: μ > 50

To do so, the researcher has 100 subjects follow the protocol described above. The mean score for these students is  = 55.2 and the P-value is less than 0.0001.

Reference: Ref 16-1

It is appropriate to conclude which of the following?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

72.

A medical researcher is working on a new treatment for a certain type of cancer. The average survival time after diagnosis on the standard treatment is two years. In an early trial, she tries the new treatment on three subjects who have an average survival time after diagnosis of four years. Although the survival time has doubled, the results are not statistically significant even at the 0.10 significance level. The explanation is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

73.

An SRS of 18 recent birth records at the local hospital was selected. In the sample, the average birth weight was 119.6 ounces and the standard deviation was 6.5 ounces. Assume that in the population of all babies born in this hospital, the birth weights follow a Normal distribution, with mean μ.

Reference: Ref 18-1

We are interested in a 95% confidence interval for the population mean birth weight. The margin of error associated with the confidence interval is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

74.

The decrease in cholesterol level after eating a certain brand of oatmeal for breakfast for one month in people with cholesterol levels over 200 is Normally distributed, with mean (in milligrams) μ and standard deviation σ = 3. The brand advertises that eating its oatmeal for breakfast daily for one month will produce a mean decrease in cholesterol of more than 10 points for people with cholesterol levels over 200, but you believe that the mean decrease in cholesterol is actually less than advertised. To explore this, you test the hypotheses

H0: μ = 10, Ha: μ < 10

and you obtain a P-value of 0.052. Which of the following is true?

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

75.

The height (in inches) of males in the United States is believed to be Normally distributed, with mean μ. The average height of a random sample of 50 American adult males is  = 69.72 inches, and the standard deviation of the 50 heights is s = 4.23. The standard error of  is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

76.

A radio show conducts a phone-in survey each morning. Listeners are asked to call in with a response to the question of the day. One morning in 2011, listeners were asked if they supported or opposed term limits for members of Congress. Remarkably, 88% of listeners that called in favored term limits. We may safely conclude that

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

77.

A special diet is intended to reduce systolic blood pressure. If the diet is effective, the target is to have the average systolic blood pressure of this group be below 150. After six months on the diet, an SRS of 28 patients with high blood pressure had an average cholesterol of  = 143, with standard deviation s = 21. Is this sufficient evidence that the diet is effective in meeting the target? Assume the distribution of the cholesterol for patients in this group is approximately Normal with mean μ.

Reference: Ref 18-2

Suppose the mean and standard deviation obtained were based on a sample of 10 patients, rather than 28. The P-value would be

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

78.

Which of the following will reduce the value of the power in a statistical test of hypotheses?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

79.

A researcher plans to conduct a test of hypotheses at the α = 0.10 significance level. She designs her study to have a power of 0.70 at a particular alternative value of the parameter of interest.

Reference: Ref 16-2

The probability that the researcher will commit a Type II error for the particular alternative value of the parameter at which she computed the power is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

80.

You are thinking of employing a t-procedure to test hypotheses about the mean of a population using a significance level of 0.05. You suspect the distribution of the population is not Normal and may be moderately skewed. Which of the following statements is correct?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

81.

A TV news program conducts a call-in poll about a proposed city ban on smoking in public places. Of the 2467 callers, 1900 were opposed to the ban. Which of the following statements are true with respect to using this sample to estimate p, the proportion of all TV news viewers that favor such a ban on smoking in public places?

Points Earned:

0/1

Correct Answer:

A

Your Response:

C

82.

The American Veterinary Medical Association conducted a survey of veterinary clinics to estimate the proportion that do not treat large animals (cows, horses, etc.). The survey was mailed to a random sample of 120 veterinary clinics throughout the country and of these, 88 responded that they do not treat large animals.

Reference: Ref 20-2

The standard error SE of the sample proportion  of clinics that do not treat large animals, is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

83.

A local board of education conducted a survey of residents in the community concerning a property tax levy on the coming local ballot. They randomly selected 850 residents in the community and contacted them by telephone. Of the 850 residents surveyed, 410 supported the property tax levy. Let p represent the proportion of residents in the community that support the property tax levy.

Reference: Ref 20-3

A 90% confidence interval for p is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

84.

In 1965, about 44% of the U.S. adult population had never smoked cigarettes. A national health survey of 1472 U.S. adults (presumably selected randomly) during 2010 revealed that 677 had never smoked cigarettes.

Reference: Ref 20-5

A 99% confidence interval for the proportion of U.S. adults in 2006 that have never smoked is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

85.

In 1965, about 44% of the U.S. adult population had never smoked cigarettes. A national health survey of 1472 U.S. adults (presumably selected randomly) during 2010 revealed that 677 had never smoked cigarettes.

Reference: Ref 20-5

Suppose you wished to test whether there has been a change since 1965 in the proportion of U.S. adults that have never smoked cigarettes. You suspect that the proportion has grown since 1965. Which of the following are the appropriate hypotheses?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

86.

A researcher has developed a new drug designed to reduce blood pressure. In an experiment, 21 subjects were assigned randomly to the treatment group, and received the new experimental drug. The other 23 subjects were assigned to the control group, and received a standard, well known treatment. After a suitable period of time, the reduction in blood pressure for each subject was recorded. A summary of these data is:

Reference: Ref 19-1

The P-value for the test described in Question 5 (again, using Option 2 for degrees of freedom) is

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

87.

A researcher has developed a new drug designed to reduce blood pressure. In an experiment, 21 subjects were assigned randomly to the treatment group, and received the new experimental drug. The other 23 subjects were assigned to the control group, and received a standard, well known treatment. After a suitable period of time, the reduction in blood pressure for each subject was recorded. A summary of these data is:

Reference: Ref 19-1

Which of the following would lead us to believe that the t-procedures were not safe to use here?

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

88.

An inspector inspects large truckloads of potatoes to determine the proportion p in the shipment with major defects prior to using the potatoes to make potato chips. Unless there is clear evidence that this proportion, p, is less than 0.10, he will reject the shipment. He will test the hypotheses

H0: p = 0.10, Ha: p < 0.10.

He selects an SRS of 200 potatoes from the over 5000 potatoes on the truck. Suppose that 12 of the potatoes sampled are found to have major defects.

Reference: Ref 20-6

Using the plus four method, a 95% confidence interval for the true proportion of potatoes in the truck that have major defects is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

89.

Is there a difference in the amount of airborne bacteria between carpeted and uncarpeted rooms? In an experiment, 7 rooms were carpeted and 7 were left uncarpeted. The rooms are similar in size and function. After a suitable period of time, the concentration of bacteria in the air was measured (in units of bacteria per cubic foot) in all of these rooms. The data and summaries are provided:

Reference: Ref 19-3

A 95% confidence interval for the difference in mean bacterial concentration in the air of carpeted rooms versus uncarpeted rooms is (use the conservative value for the degrees of freedom)

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

90.

DDT is a pesticide banned in the United States for its danger to humans and animals. In an experiment on the impact of DDT, 6 rats were exposed to DDT poisoning and 6 rats were not. For each rat in the experiment, a measurement of nerve sensitivity was recorded. The researchers suspected that the mean nerve sensitivity for rats exposed to DDT is greater than that for rats not poisoned. The data follow:

Let  be the mean nerve sensitivity for rats poisoned with DDT. Let  be the mean nerve sensitivity for rats not poisoned with DDT.

Reference: Ref 19-4

The numerical value of the standard error of the difference in sample means is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

91.

In the United States, there is a strong relationship between smoking and education, with well-educated people less likely to smoke. A study in France included a sample of 459 men who were selected at random from men who had visited a health center for a routine checkup. Education is classified into three categories corresponding to the highest level of education and smoking status is classified into four categories.                     Smoking Status

Reference: Ref 23-1

Suppose we wish to test the null hypothesis that there is no association between education level and smoking status. Under the null hypothesis, the expected number of nonsmokers with a primary school education is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

92.

In the United States, there is a strong relationship between smoking and education, with well-educated people less likely to smoke. A study in France included a sample of 459 men who were selected at random from men who had visited a health center for a routine checkup. Education is classified into three categories corresponding to the highest level of education and smoking status is classified into four categories.                     Smoking Status

Reference: Ref 23-1

The degrees of freedom for the chi-square test for this two-way table are

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

93.

Recent revenue shortfalls in a southern state led to a reduction in the state budget for higher education. To offset the reduction, the largest state university proposed a 20% tuition increase. It was determined that such a large increase was needed to simply compensate for lost support from the state. Random samples of 100 freshmen, 100 sophomores, 100 juniors, and 100 seniors from the university were asked whether they were strongly opposed to the increase, given that it was the minimum increase necessary to maintain the university's budget at current levels. The results are given in the following table.

Reference: Ref 23-2

To compare the four classes (freshman, sophomore, junior, senior) with respect to their opinion regarding the proposed tuition increase (yes = opposed, no = not opposed), which distribution should we calculate?

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

94.

Recent revenue shortfalls in a southern state led to a reduction in the state budget for higher education. To offset the reduction, the largest state university proposed a 20% tuition increase. It was determined that such a large increase was needed to simply compensate for lost support from the state. Random samples of 100 freshmen, 100 sophomores, 100 juniors, and 100 seniors from the university were asked whether they were strongly opposed to the increase, given that it was the minimum increase necessary to maintain the university's budget at current levels. The results are given in the following table.

Reference: Ref 23-2

What is the contribution to the chi-square statistic from the cell of strongly opposed juniors?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

95.

A random sample of Ohio voters was asked about the number of cars or trucks they own (one, two, or at least three) and the type of community they lived in (rural, suburban, urban). The two-way table follows.

Reference: Ref 23-3

The proportion of rural residences with at least three cars or trucks is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

96.

Do women and men treat female and male children differently? An observational study was conducted near the primate exhibit at the Columbus Zoo on weekends in 1997. The data are from 39 groups of three—one adult female, one adult male, and one toddler, in which the toddler was being carried. Recorded below is which adult (male or female) was carrying the toddler by the sex of the toddler. 

Reference: Ref 23-4

The numerical value of the chi-square statistic for testing independence of sex of the adult and sex of the toddler is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

97.

To study the export activity of manufacturing firms in Korea, questionnaires were mailed to an SRS of firms in each of three industries that export many of their products. The response rate was low, and to compare the industries it is important that the response rates from the different industries be similar. Do the data in the Minitab output shown in the following table provide evidence of a difference in response rate between the four industries? The output includes the cell counts, the expected cell counts, and the chi-square statistic. Expected counts are printed below observed counts

Chi-Sq = 4.754

Reference: Ref 23-5

The P-value for testing the null hypothesis that the probability of response is the same for the three industries against the alternative that the probability is different for the three industries

Points Earned:

0/1

Correct Answer:

A

Your Response:

B

98.

A candidate for one of Ohio's two U.S. Senate seats wishes to compare her support among registered voters in the northern half of the state with her support among registered voters in the southern half of the state. A random sample of 2000 registered voters in the northern half of the state is selected, of which 1062 support the candidate. Additionally, a random sample of 2000 registered voters in the southern half of the state is selected, of which 900 support the candidate.

Reference: Ref 21-1

Using the large-sample estimate, we estimate that the proportion of registered adults in the northern half of the state who support this candidate is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

99.

In a large midwestern university (the class of entering freshmen is 6000 or more students), an SRS of 100 entering freshmen in 1999 found that 20 finished in the bottom third of their high school class. Admission standards at the university were tightened in 1995. In 2001, an SRS of 100 entering freshmen found that 10 finished in the bottom third of their high school class. Let  and  be the proportion of all entering freshmen in 1999 and 2001, respectively, who graduated in the bottom third of their high school class.  Is there evidence that the proportion of freshmen who graduated in the bottom third of their high school class in 2001 has been reduced, as a result of the tougher admission standards adopted in 2000, compared to the proportion in 1999? To determine this, you test the hypotheses

H0: p1 = p2, Ha: p1 > p2.

Reference: Ref 21-2

A 99% confidence interval for  is

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

100.

An SRS of 100 flights of a large airline (airline 1) showed that 64 were on time. An SRS of 100 flights of another large airline (airline 2) showed that 80 were on time. Let p1 andp2 be the proportion of all flights that are on time for these two airlines.

Reference: Ref 21-3

Is there evidence of a difference in the on-time rate for the two airlines? To determine this, you test the hypotheses

H0: p1 = p2, Ha: p1 ≠ p2.

The P-value of your test of the hypotheses given is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B