Intro statistics

Points Awarded

 95

Points Missed

 5

Percentage

 95%

1.

A description of different houses for sale includes the following variables. Which of the variables is categorical?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

2.

As part of a data base on new births at a hospital, some variables recorded are the age of the mother, marital status of the mother (e.g., single, married, divorced), weight of the baby, and sex of the baby. Of these variables

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

3.

A large university is divided into six colleges, with most students graduating from four of these colleges. The following bar chart gives the distribution of the percent graduating from the four most popular colleges in 2003.

Reference: Ref 1-2

Which of the following is a correct statement?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

4.

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 histogram

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

5.

The stemplot below displays midterm exam scores for the 34 students taking a Calculus course. The highest possible test score was 100. The teacher declared that an exam grade of 65 or higher was good enough for a grade of “C” or better.

Reference: Ref 1-5

The percent of students earning a grade of “C” or higher (as declared by the teacher) is closest to

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

6.

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

Reference: Ref 2-2

The median age (in years) of the faculty members at Wilmington State is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

7.

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

If each person increased his or her score by 5 points then

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

8.

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

9.

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

10.

A group of 4 friends has median age 22. Three of them are aged 20, 18, and 24. The age of the fourth friend must be

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

11.

Do men with more children have higher blood pressure? In a study, blood pressures of men with more than three children were compared with those of men with three or fewer children. Which of the following is true for this study?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

12.

Archaeologists often find only parts of ancient human remains. For example, they may find a small finger bone, called the metacarpal bone. Is it possible to predict the height of a human from the length of his or her metacarpal bone? To investigate, a researcher measures the heights and metacarpal lengths of 200 adults. In making the scatterplot, the researcher should

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

13.

For each menu item at a fast food restaurant, fat content (in grams) and number of calories were recorded. A scatterplot of these data is given:

Reference: Ref 4-3

Suppose we changed the units of fat from grams to ounces. Which of the following statements is correct?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

14.

Which of the following is true of the correlation coefficient r?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

15.

Use the following density curve to answer the question(s) below.

Reference: Ref 3-1

For this density curve, the third quartile is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

16.

Using the standard Normal distribution tables, the area under the standard Normal curve corresponding to Z > –1.62 is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

17.

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

18.

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

What proportion of boxes is underweight (i.e., weigh less than 32 oz)?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

19.

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

20.

Scores on the SAT verbal test in recent years follow approximately the N(515, 109) distribution.

Reference: Ref 3-8

The proportion of students scoring between 460 and 550 is closest to

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

21.

The least-squares regression line is

Points Earned:

0/1

Correct Answer:

B

Your Response:

D

22.

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

23.

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

24.

The correlation between the height and weight of children aged 6 to 9 is found to be about r = 0.8. Suppose we use the height x of a child to predict the weight y of the child. We conclude

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

25.

The following is a scatterplot for profits versus sales (in tens of thousands of dollars) for a sample of 14 large companies. The correlation between Sales and Profits is 0.949.

Reference: Ref 5-3

From this information we see

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

26.

Curiously, during months when sales of beer are above average, sales of ice cream also tend to be above average; during months when sales of beer are below average, sales of ice cream also tend to be below average. Which of the following can we conclude from these facts?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

27.

A newspaper article is summarized: According to a new study, teachers may be more inclined to give higher grades to students, hoping to gain favor with the university administrators who grant tenure. The study examined the average grade and teaching evaluation in a large number of courses given in 1997 in order to investigate the effects of grade inflation on evaluations. “I am concerned with student evaluations because instruction has become a popularity contest for some teachers,” said Professor Smith, who recently completed the study. Results showed higher grades directly corresponded to a more positive evaluation.

Reference: Ref 5-4

Which of the following would be a valid conclusion to draw from the study?

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

28.

A survey of undergraduate college students at a small university was recently done by an administrator in charge of residential life services. A random sample of 300 students was selected from each class level (freshman, sophomore, junior, senior). Each student was asked to complete and return a short questionnaire on quality of campus residence. Some students returned the questionnaire, and some didn't. This is summarized in the table below:

Reference: Ref 6-1

Which of the following conclusions seems to be supported by the data?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

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

Of the students that feel campus residences are of high quality, what percent are seniors?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

30.

In a study of the link between high blood pressure and cardiovascular disease, a group of white males aged 35 to 64 was followed for five years. At the beginning of the study, each man had his blood pressure measured and it was classified as either “low” systolic blood pressure (less than 140 mm Hg) or “high” blood pressure (140 mm Hg or higher). The following table gives the number of men in each blood pressure category and the number of deaths from cardiovascular disease during the five-year period.

Based on these data, which of the following statements is correct?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

31.

Sickle-cell disease is a painful disorder of the red blood cells that in the United States affects mostly blacks. To investigate whether the drug hydroxyurea can reduce the pain associated with sickle-cell disease, a study by NIH gave the drug to 150 sickle-cell sufferers and the placebo to another 150. Neither doctors nor patients were told who received the drug. The number of episodes of pain reported by each subject was recorded. This is an example of

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

32.

In order to investigate treatments for morbid obesity, obese subjects satisfying fairly strict requirements were randomly assigned to one of three groups: gastric bypass surgery; participation in a diet and exercise program; or both gastric bypass surgery and participation in the diet and exercise program. Researchers carefully observed the amount of weight lost five years after the study began.

Reference: Ref 9-1

This study has

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

33.

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

This is an example of

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

34.

A researcher finds 2000 mildly overweight women who exercise regularly, have not had a heart attack, and are willing to participate in the study. She randomly assigns 500 of the women to take an appetite suppressant. The other 500 women are given a placebo. Both groups are followed for five years and the amount of weight lost after this time is recorded.

Reference: Ref 9-4

The factor in the experiment is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

35.

Medical researchers are excited about a new cancer treatment that destroys tumors by cutting off their blood supply. To date, the treatment has only been tried on mice, but in mice it has been nearly 100% effective in eradicating tumors and appears to have no side effects. As evidence of the effectiveness of the new treatment in treating cancer in humans, these studies

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

36.

Each month, the census bureau mails survey forms to 250,000 households asking questions about the people living in the household and about such things as motor vehicles and housing costs. Telephone calls are made to households that don't return the form. In one month, responses were obtained from 240,000 of the households contacted.

Reference: Ref 8-1

The population of interest is

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

37.

Import customs officials sometimes randomly select crates of cargo for close, but time-consuming, inspection. Suppose there are nine crates of cargo from the following companies, and customs officials will randomly select four for close inspection. 

To do this, use the numerical labels attached to the previous names and the following list of random digits. Read the list of random digits from left to right, starting at the beginning of the list. 748803 12009 45287 71753 98236 66419 84533 11793 20495 05907 11384

Reference: Ref 8-4

The simple random sample is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

38.

The magazine High Times has a website that once asked visitors whether recreational marijuana use should be legal. This is an example of

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

39.

Advice columnist Ann Landers once asked her readers with children to answer the following question: “If you had it to do over again, would you have children?” Readers were invited to send a response to this question by mail. Of the approximately 10,000 responses Landers received, approximately 70% said “no.”

Reference: Ref 8-5

The sample is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

40.

A public opinion poll in Ohio wants to determine whether registered voters in the state approve of a measure to ban smoking in all public areas. The researchers select a simple random sample of 50 registered voters from each county in the state and ask whether they approve or disapprove of the measure. This is an example of

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

41.

The law of large numbers states that as the number of observations drawn at random from a population with finite mean μ increases, the mean  of the observed values

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

42.

Suppose you want to estimate the average number of sick days taken by all employees at a large company during a year. Suppose (unknown to you) this is 4 days. You devise a way to randomly select 200 employees for a survey and use the sample mean number of sick days as an estimate of the population mean for all workers at the company. Unknown to you, the sampling distribution of the sample mean has an average value of 4.8. This means that

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

43.

A statistic is said to be unbiased if

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

44.

Suppose a large population has mean μ and standard deviation σ, and a simple random sample of size n is taken. The sampling distribution of the sample mean  has mean and variance respectively equal to

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

45.

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

46.

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

If 100 bags of cookies are selected randomly, the probability that the sample mean will be between 15.84 and 16.16 ounces is

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

47.

You randomly select 500 students and observe that 85 of them smoke. Estimate the probability that a randomly selected student smokes.

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

48.

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

Reference: Ref 10-1

If you bet on red, the probability of winning is 18/38 = 0.4737. The probability 0.4737 represents

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

49.

According to the Current Population Survey, the following table summarizes probabilities for randomly selecting a full-time student in various age groups:

Reference: Ref 10-3

If we randomly select a full-time student, what is the probability that he/she is 25 or older?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

50.

You roll a pair of fair dice and compute the number of spots on the two sides facing up. Denote this total by X. The probability distribution of X is

Reference: Ref 10-9

The probability that X is a 2, 11, or 12 is

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

51.

A set of 20 cards consists of 12 red cards and 8 black cards. The cards are shuffled thoroughly 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 is done a total of six times. Let X be the number of red cards observed in these six trials. The variance of X is

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 win at most once is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

53.

If X has a binomial distribution with 20 trials and a mean of 6, then the success probability p is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

54.

At a large Midwestern college, 4% of the students are Hispanic. A random sample of 20 students from the college are selected. Let X denote the number of Hispanics among them.

Reference: Ref 13-2

The mean of X is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

55.

An article in Parenting magazine reported that 60% of Americans needed a vacation after visiting their families for the holidays. Suppose this is the true proportion of Americans who feel this way. A random sample of 100 Americans is taken. What is the probability that less than 50% of the people in the sample feel that they need a vacation after visiting their families for the holidays?

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.

Spelling mistakes in a text are either “nonword errors” or “word errors.” A nonword error produces a string of letters that is not a word, such as “the” typed as “teh.” Word errors produce the wrong word, such as “loose” typed as “lose.” Nonword errors make up 25% of all errors. A human proofreader will catch 80% of nonword errors and 50% of word errors.

Reference: Ref 12-4

What percent of errors will the proofreader catch?

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

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

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

59.

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 at least $9 in total on the two plays of the game is

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

60.

Event A occurs with probability 0.3, and event B occurs with probability 0.4. If A and B are independent, we may conclude

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

61.

The upper 0.05 critical value of the standard Normal distribution is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

62.

In formulating hypotheses for a statistical test of significance, the null hypothesis is often

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

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.

Is the mean age at which American children can first read now under 4 years? If the population of all American children has mean age of μ years until they begin to read, one would test which of the following null and alternative hypotheses to answer this question?

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

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

The P-value of the test of the null hypothesis is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

66.

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

67.

A company produces precision 1 meter (1000 mm) rulers. The actual distribution of lengths of the rulers produced by this company is Normal, with mean μ and standard deviationσ = 0.02 mm. Suppose I select a simple random sample of four of the rulers produced by the company and I measure their lengths in mm. The results of these four measurements are

Based on these data, a 90% confidence interval for μ is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

68.

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

69.

The time (in number of days) until maturity of a certain variety of tomato plant is Normally distributed with mean μ and standard deviation σ = 2.4. I select a simple random sample of four plants of this variety and measure the time until maturity. The four times, in days, are

Reference: Ref 14-3

If I wanted the margin of error for the 95% confidence interval to be ± 1 inch, I should select a simple random sample of size

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

70.

A level α two-sided significance test does not reject the null hypothesis H0:μ = μ0 when

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

71.

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

72.

In assessing the validity of any test of hypotheses, it is good practice to

Points Earned:

0/1

Correct Answer:

A

Your Response:

D

73.

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

74.

Does 30 minutes of meditation every day provide significant improvement in mental performance? To investigate this issue, a researcher conducted a study with 150 adult subjects who meditated for 30 minutes each day for a period of six months. At the end of the study, 300 variables related to the mental performance of the subjects were measured on each subject and the means compared to known means for these variables in the population of all adults. Sixteen of these variables were significantly better (in the sense of statistical significance) at the α = 0.05 level for the group that performed 30 minutes of meditation each day as compared to the population as a whole, and three variables were significantly better at the α = 0.01 level for the group that performed 30 minutes of meditation each day as compared to the population as a whole. It would be correct to conclude that

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

75.

A Type I error is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

76.

The reduction 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 = 8. Although the brand advertises that eating their oatmeal for breakfast daily for one month will produce a mean decrease in cholesterol of more than 20 points for people with cholesterol levels over 200, you believe that the mean decrease in cholesterol is actually less than advertised. To explore this, you test the hypotheses

H0: μ = 20, Ha: μ < 20

at the 0.05 level. You will do this by randomly selecting 144 people with cholesterol levels over 200 and, after eating this brand of oatmeal for one month, computing the mean decrease  in cholesterol levels of the subjects. If you observe a sample mean cholesterol reduction of  = 18.52, the P-value obtained is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

77.

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

78.

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

A 95% confidence interval for the average blood pressure of all similar patients who have been on the diet for 6 months is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

79.

We wish to see if, on average, traffic is moving at the posted speed limit of 65 miles per hour along a certain stretch of Interstate 70. On each of four randomly selected days, a randomly selected car is timed and the speed of the car is recorded. The observed speeds are 70, 65, 70, and 75 miles per hour. Assuming that speeds are Normally distributed with mean μ, we test whether, on average, traffic is moving at 65 miles per hour, by testing the hypotheses H0: μ = 65, Ha: μ ≠ 65.

Reference: Ref 18-3

Based on the data, the value of the one-sample t statistic is

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

80.

The water diet requires one to drink two cups of water every half hour from when one gets up until one goes to bed, but otherwise allows one to eat whatever one likes. Four adult volunteers agree to test the diet. They are weighed prior to beginning the diet and after six weeks on the diet. The weights (in pounds) are

For the population of all adults, assume that the weight loss after six weeks on the diet (weight before beginning the diet minus weight after six weeks on the diet) is Normally distributed with mean μ.

Reference: Ref 18-5

A 95% confidence interval for μ based on these data is

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

81.

Each person in a random sample of 2000 “likely voters” (as defined by a professional polling organization) was questioned about his or her political views. Of those surveyed, 1308 felt that “the economy's state” was the most urgent national concern.

Reference: Ref 20-1

Using the plus four estimate,, we estimate the proportion of likely voters that felt the economy's state was the most urgent national concern to be

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

82.

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:

1/1

Correct Answer:

A

Your Response:

A

83.

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

84.

Do SAT coaching classes work? Do they help students to improve their test scores? Four students were selected randomly from all of the students that completed an SAT coaching class. For each student, we recorded their first SAT score (before the class) and their second SAT score (after the coaching class).

To analyze these data, we should use

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

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

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 researcher suspects that the new drug results in greater average reduction in blood pressure than the old drug does. Based on these data, the computed two-sample tstatistic is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

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

If we had used the more accurate software approximation to the degrees of freedom, we would have used which of the following for the approximate number of degrees of freedom for the t-procedures?

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

88.

A sports writer wished to see if a football filled with helium travels farther, on average, than a football filled with air. To test this, the writer used 20 adult male volunteers. These volunteers were randomly divided into two groups of 10 subjects each. Group 1 kicked a football filled with helium to the recommended pressure. Group 2 kicked a football filled with air to the recommended pressure. The mean yardage for group 1 was  = 32 yards, with a standard deviation s1 = 9 yards. The mean yardage for group 2 was  = 27 yards, with a standard deviation s2 = 6 yards. Assume the two groups of kicks are independent. Let μ1 and μ2 represent the mean yardage we would observe for the entire population represented by the volunteers if all members of this population kicked, respectively, a helium and an air-filled football. Assume that two-sample t-procedures are safe to use.

Reference: Ref 19-2

Suppose the researcher had wished to test the hypotheses

The numerical value of the two-sample t statistic is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

89.

A sports writer wished to see if a football filled with helium travels farther, on average, than a football filled with air. To test this, the writer used 20 adult male volunteers. These volunteers were randomly divided into two groups of 10 subjects each. Group 1 kicked a football filled with helium to the recommended pressure. Group 2 kicked a football filled with air to the recommended pressure. The mean yardage for group 1 was  = 32 yards, with a standard deviation s1 = 9 yards. The mean yardage for group 2 was  = 27 yards, with a standard deviation s2 = 6 yards. Assume the two groups of kicks are independent. Let μ1 and μ2 represent the mean yardage we would observe for the entire population represented by the volunteers if all members of this population kicked, respectively, a helium and an air-filled football. Assume that two-sample t-procedures are safe to use.

Reference: Ref 19-2

Suppose the researcher had wished to test the hypotheses

The P-value for the test is (use the conservative Option 2 for the degrees of freedom)

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

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 t statistic is

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

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

This is an r  c table. The number c has value

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:

0/1

Correct Answer:

C

Your Response:

B

94.

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

Suppose we wish to test the null hypothesis that the proportion of male adults and the proportion of female adults carrying a toddler is the same, regardless of the sex of the toddler. Under the null hypothesis, the expected number of male adults who would be carrying a female toddler according to the table is

Points Earned:

1/1

Correct Answer:

B

Your Response:

B

95.

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:

0/1

Correct Answer:

A

Your Response:

D

96.

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

This is an r   c table. The number r has value

Points Earned:

1/1

Correct Answer:

C

Your Response:

C

97.

A study examines the personal goals of children in grades 4, 5, and 6. A random sample of students was selected for each of the grades 4, 5, and 6 from schools in Georgia. The students received a questionnaire regarding achievement of personal goals. They were asked what they would most like to do at school: make good grades, be good at sports, or be popular. Results are presented in the following table by the sex of the child.

Reference: Ref 23-6

Which hypotheses are being tested by the chi-square test?

Points Earned:

1/1

Correct Answer:

A

Your Response:

A

98.

A study examines the personal goals of children in grades 4, 5, and 6. A random sample of students was selected for each of the grades 4, 5, and 6 from schools in Georgia. The students received a questionnaire regarding achievement of personal goals. They were asked what they would most like to do at school: make good grades, be good at sports, or be popular. Results are presented in the following table by the sex of the child.

Reference: Ref 23-6

The data are going to be summarized by the researchers computing the conditional distributions of personal goals for boys and girls. For what proportion of girls is it most important to make good grades?

Points Earned:

1/1

Correct Answer:

D

Your Response:

D

99.

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

100.

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:

0/1

Correct Answer:

D

Your Response:

B