Stat200

STAT200

1. The newspaper reports that higher rates of sunburn and ice cream consumption correspond. Does that mean that eating ice cream can put you at risk of sunburn? What might be the reason behind this phenomenon?

a. Kids are not waiting 40 minutes after eating to swim

b. In summer both ice cream consumption and rates of sunburn increase

c. Eating ice cream is viewed as a replacement for sunblock

2. A prospective graduate student may be interested in class size at the university s/he will attend. Data on how many students were in last years incoming class is an example of:

a. Descriptive statistics

b. Inferential statistics

3. The following distribution has:

 

a. A positive skew

b. A left skew

c. No skew

4. A normal or bell shaped distribution has its greatest probability density in the middle.

a. True

b. False

5. Which of the following is a qualitative variable?

a. Weight in pounds

b. Number of days of precipitation

c. Race

d. Average daily high temperature

6. Identify the scale of measurement for the following: temperature measured in centigrade

a. Nominal

b. Ordinal

c. Interval

d. Ratio

7. For the following data:  

a. 1

b. 16

c. 49

d. 7

8. The lowest value in the dataset is (multiply stems by 10.0):  

a. 19

b. 13.2

c. 13

d. 1.9

9. The following bar chart shows percent increase in the consumer price index for four three-month periods ending the date shown: In which quarter did the CPI increase the most, in percentage terms?

a. the quarter ending July 2000

b. the quarter ending October 2000

c. the quarter ending January 2001

d. the quarter endinig April

10. For the following histogram of test scores, The majority of scores came between______

a. 39.5 and 49.5

b. 89.5 and 99.5

c. 79.5 and 89.5

d. 159.5 and 169.5

11. For the following line graph of quarterly percentage changes in five components of the CPI, which component steadily increased from quarter to quarter?

 

a. Housing

b. Medical Care

c. Food and Beverage

d. Recreation

e. Transportation

12. The area under the curve of a probability distribution is _____

a. 0

b. 100

c. .68

d. 1

13. Which of the following is a qualitative variable?

a. Weight in kilograms

b. Number of days without precipitation

c. Ethnicity

d. Average daily temperature

14. The highest value in the dataset is (multiply stems by 10.0):  

a. 132

b. 13.2

c. 13

d. 1.32

15. Low-density lipoprotein (LDL) is an important part of blood cholesterol test. LDL higher than 130mg/dl is a risk factor of developing cardiovascular disease. To prevent cardiovascular disease, a health center had a free blood cholesterol test for all the people older than 65 in the community. A total of eight people attended the blood screening and their blood test results are listed below: LDL(mg/dl): 130,143,114,110,123,110,134,124 After the blood test, the nurse wants to know the variance of LDL scores

16. Rachael and Peter are discussing how the mean value and variance affect the distribution graph. As the following graph shows, there are two distributions: A and B Peter said that the distribution A has fatter tail because its has bigger standard deviation than the distribution B. Rachael's answer is different:she thinks the distribution A has a smaller standard deviation than the distribution B. Who do you think is right?

a. Peter

b. Rachael

c. None of them are right. Distribution A and Distribution B have the same standard Deviation

17. The singular form of the word “dice” is “die”. Tom was throwing a six-sided die. The first time he threw, he got a three; the second time he threw, he got a three again. What’s the probability of getting a three at the third time?

18. Rachel was flipping a coin with Jerry. She told jerry: “I am able to get all heads in two tosses.” Jerry laughed at her: “No, the probability of getting two heads at two tosses is only__”

19. Jennie and Alex both wanted to get a free ticket for a College Music concert. However, the concert staff told them the tickets were limited. Twenty people wanted to attend the concert but only 10 free tickets were left. So the concert center staff decided to use a lottery to decide who would receive the free tickets. What’s the probability of Jennie and Alex both getting free tickets?

20. Laura and Melissa were playing dice. What the probability of Laura and Melissa both getting a 6?

21. In a statistics class with 36 students, the professor wanted to know the probability that at least two students share the same birthday. The probability will be___

a. 0.1

b. Much smaller than 0.1

c. Much bigger than 0.1

d. Not possible

22. If you throw a die for two times, what is the probability that you will get a one on the first throw or a one on the second throw (or both)?

23. Jerry got a box full of colorful candy balls. There were 50 of them: 20 red, 10 green, 12 yellow and 8 blue. After shaking the box, he randomly selected 2 candy balls from the box. What’s the probability that the first one was blue and the second one was yellow?

24. Which activity could probabilities be computed using a Binomial Distribution?

a. Flipping a coin a 100 times

b. Throwing a die one hundred times

c. The probability of getting a heart while playing card games

d. Grades earned by 100 students on a statistics final exam

25. Many researchers have argued that the TB skin test is not accurate. Imagine that the TB skin test is only 70% accurate. Sarah is thinking about having the test. Before she has the test she wonders the probability that she has TB. The probability of Sarah having TB is …

a. 70%

b. 35%

c. 30%

d. More information needed to calculate

26. Imagine that the diabetic test accurately indicates the disease in 95% of the people who have it. What’s the miss rate?

27. Which of the following is the probability that subjects do not have the disease, but the test result is positive?

a. Miss rate

b. False positive rate

c. Base rate

d. Disease rate

28. In a normal distribution, the median is ____it’s mean and mode.

a. Approximately equal to

b. Bigger than

c. Smaller than

d. Unrelated to

29. In a normal distribution, __ percentage of the area under the curve is within one standard deviations of the mean?

a. 68%

b. 100%

c. 95%

d. It depends on the values of the mean and standard deviation

30. A normal distribution with a mean of 15 and standard deviation of 5. 95% of its area is within__

a. One standard deviation of the mean

b. Two standard deviations of the mean

c. Three standard deviations of the mean

d. It depends on the value of the mode

31. The mean of a standard normal distribution is:

a. 0

b. 1.0

c. -1.0

d. 100

32. The standard deviation of the mean for a standard distribution is:

a. 0.0

b. 1.0

c. 100

d. 68%

33. A normal distribution with a mean of 25 and standard deviation of 5. What is the corresponding Z score for a case having a value of 10?

34. Consider a normal distribution with a mean of 25 and standard deviation of 4. Approximately, what proportion of the area lies between values of 17 and 33.

a. 95%

b. 68%

c. 99%

d. 50%

35. Consider a normal distribution with a mean of 10 and standard deviation of 25. What’s the Z score for the value of 35?

36. For a standard normal distribution, what’s the probability of getting a positive number?

a. 50%

b. 95%

c. 68%

d. We cannot tell from the given information

37. Two-hundred students took a statistics class. Their professor creatively decided to give each of them their Z-score instead of their grade. Rachel got her Z-score of -0.2. She was wondering how well she did on the exam.

a. It was very good, much better than almost all of the other students

b. It was so-so, but still better than half of the students.

c. It was not that good, but not at the bottom of the distribution

d. It was very bad and she needs to work much harder next time

38. A researcher collected some data and they form a normal distribution with a mean of zero. What’s the probability of getting a positive number from this distribution?

a. 25%

b. 50%

c. 75%

d. We need to calculate the standard deviation and then decide.

39. Which of the following description of distribution is correct?

a. A Binomial distribution is a probability distribution for independent events for which there are only two possible outcomes

b. You cannot use the normal distribution to approximate the binomial distribution

c. Normal distributions cannot differ in their means and in their standard deviations.

d. Standard normal distributions can differ in their means and in their standard deviations.

40. A toy factory makes 5,000 teddy bears per day. The supervisor randomly selects 10 teddy bears from all 5,000 teddy bears and uses this sample to estimate the mean weight of teddy bears and the sample standard deviation. How many degrees of freedom are there in the estimate of the standard deviation?

41. Imagine you have a population of 100,000 cases. For which of the following degrees of freedom is the closest estimation of the population parameter?

a. 4

b. 6

c. 10

d. 1000

42. Imagine that the average weight of a total of 500 girls in a high school is 35kg. Tom randomly sampled 10 girls and measured their weight. And then he repeated this procedure for three times. The means and standard deviations are listed as following. Which sample estimate shows the least sample variability?

a. Sample one: mean=34, SE=5

b. Sample two: mean=30, SE=2

c. Sample three: mean= 26, SE=3

d. Sample four: mean= 38, SE=5

43. For which of the following degrees of freedom is a t distribution closest to a normal distribution?

a. 10

b. 20

c. 5

d. 1000

44. In order to construct a confidence interval for the difference between two means, we are going to assume which of the followings? (Select all that apply)

a. The two populations have the same variance.

b. The populations are normally distributed.

c. Each value is sampled independently from each other value.

d. The two populations have similar means

45. A researcher tries to compare grades earned on the first quiz by boys and girls. He randomly chooses 10 students from boys and 15 students from girls and calculates the confidence interval on difference between means. How many degrees of freedom will you get in this t distribution?

46. Which of the following descriptions of the t distribution is correct? (Select all that apply)

a. With smaller sample sizes, the t distribution is leptokurtic

b. When the sample size is large (more than 100), the t distribution is very similar to the standard normal distribution

c. With larger sample sizes, the t distribution is leptokurtic

d. The t distribution will never be close to normal distribution

47. _________________refers to whether or not an estimator tends to overestimate or underestimate a parameter. ______________refers to how much the estimate varies from sample to sample.

a. Bias; sample variability

b. Sample variability; Bias

c. Mean; standard deviation

d. Standard deviation; Mean

48. Which of the following descriptions of confidence intervals is correct?

a. Confidence intervals can only be computed for the mean

b. We can only use the normal distribution to compute confidence intervals

c. Confidence intervals can be computed for various parameters

d. Confidence intervals can only be computed for the population

49. In a histogram, frequencies are represented by_______

a. Lines

b. Bars

c. Portions of the pie

d. Leaves

50. What is the best measure of central tendency for the following set of numbers? 98,78,56,23,587

a. Mean

b. Mode

c. Median

d. Standard Deviation