# what is their median age?

The Johnsons have 7 children. Their ages are: 9, 15, 2, 4, 8, 10, 14

1. What is their median age?

a) 4

b) 15

c) 9

d) 2*

2. What is the IQR of their ages

a) 10*

b) 15

c) 20

d) 25

3. Researcher has 100 test subjects to split into his treatment and control groups. In order to prove any causal relationship between treatment and outcome, he should:

a) Split the subjects according to median they have taken prior*

b) Split the subjects randomly into treatment and control groups

c) Split the subject according to weight, with all heavy subjects in the control

d) Allow the subjects to choose which group they are more comfortable in

4. Was how your online popularity compares to others, you collect data on how many anyone you know has. Number of Facebook friends is an example of:

a) A categorical variable

b) A numerical variable*

c) A scatterplot

d) The internet

The histogram below (Right-Skewed) shows the distribution of 100 computer-generated exponential random variables. Use it to answer questions (5) and (6).

5. Which is true of the distribution:

a) The mean is greater than the median*

b) The median is greater than the mean

c) It is bi-modal, showing evidence of two unique groups

d) It is symmetric and approximately Normal.

6. To measure the spread (a. k. a. variability) in the distribution, we would prefer:

a) The mean

b) The IQR

c) The standard deviation*

d) The empirical rule

7. Which of the following histogram has the SMALLEST standard deviation?

a)

b)

c)

8. Which is a possible value for the correlation of X and Y in the

a) -0.75

b) 0

c) +1

d) +0.98*

A study of breakfast cereals looked at the potassium content (in milligrams) and fiber content of a large sample of cereals. A linear regression model was appropriate and produced the wing model. Use it for question (9)-(12)

Predicted Potassium=35+25*Fiber

9. A cereal having 3 grams of fiber is predicted to have how much potassium?

a) 110 mg*

b) 250mg

c) 64 mg

d) 35 mg

10. Intercept says that a cereal with 0 grams of fiber is expected to have how many of potassium?

a) 25

b) 35*

c) 45

d) 55

11. For a cereal with 10 grams of fiber, the model predicts 285 mg of potassium. Assume an 10 gram of fiber contains 280 mg of potassium. Is the residual negative or positive?

a) Positive

b) Negative*

12. The slope of the line tells us:

a) For every additional gram of fiber, we expect an additional 25 mg of potassium*

b) For every additional mg of potassium, we expect an additional 25 gram

c) That the correlation between potassium and fiber is negative

d) Nothing

Wildlife researchers monitor the length and weight of the local weight of the alligator population. The measure population is 645 lbs with a standard deviation of 124 lbs and the mean length is a standard deviation of 16 inches. The correlation for the positive relationship between the variables is 0.88. use for equation (13)-(15)

13. What is slope of the linear regression models for predicting alligators weight (y-variable) in pounds from its length (x-variable) in inches?

a) 1.28

b) 3.74

c) 6.83*

d) 0.13

14. What is the value of R?

a) 0.88

b) 0.12

c) 1.00

d) 0.77*

15. R^2 measures:

a) The percent of variation if alligator weight explained by alligator length*

b) The number of alligators in the sample

c) The percent of predicted alligator weights that will be correct

d) The average weight of an alligator

16. Are the events “Getting an A+ on this exam” and “Getting an F- on this exam” disjoint?

a) Yes*

b) No

Use the above table summarizing data on bike and car ownership by questions (17)-(19)

17. What percent of students at this college own a bike or a car?

a) 5%

b) 50%*

c) 80%

d) 35%

18. Are owning a bike and owning a car independent events?

a) Yes*

b) No

19. What is the probability a randomly chosen student has neither a car nor a bike?

a) 20%*

b) 15%

c) 50%

d) 35%

Stats quiz has 4 multiple-choice questions on it with four choices each. A student failed to so will guess randomly. Assume the outcome of any question is independent of any questions (20) and (21)

20. What is the probability the student gets the first three right and the last one wrong?

a) 0.354

b) 0.169*

c) 0.836

d) 0.012

21. What is the probability the student gets at least one question wrong?

a) 0.882

b) 0.425

c) 0.996

d) 0.009

22. A store owner knows that any customer walking something. What is the probability that 3 of the next 6 cu

a) 0.235

b) 0.450

c) 0.872

d) 0.997

Use the following information for questions (23)-(26). Male players at the high school, college and professional ranks use a regulation basketball that weighs 22.0 ounces with a standard deviation of 1.0 ounce. Assume that the weights of basketballs are approximately normallydistributed.

23. What percentage of regulation basket balls weigh less than 20.7 ounces?

a) 40.3%

b) 22.3%

c) 9.7%

d) 5.7%*

24. What is the probability a basketball weights more than 20.7 ounces?

a) 10.3%

b) 28.5%

c) 19.7%

d) 90.3%

25. If a regulation basketball is randomly selected, what is the probability that it will weigh with between 20.5 and 23.5 ounces?

a) 0.267

b) 0.134*

c) 0.866

d) 0.704

26. Statisticians generally use a guideline that says that events that happen 5% of the time less often should be considered “unusual.” By this standard, is it unusual to find a basketball that weighs 25 ounces or more?

a) Yes. This would be unusual

b) No. this would not be unusual

27. What is the weight of a basketball at the 90^{th} percentile?

a) 22.84

b) 22.00

c) 23.28

d) 23.96

28. Which of the following statements is true about a sampling distributed

a) It is used for making inferences about a sample

b) It is the probability distribution of a statistics

c) It tells us the exact value of a population parameter

d) All the above statements are true

29. When constructing a confidence interval, if the level of confidence increase error will:

a) Increase

b) Decrease*

Suppose 60% of people now own smartphones. Assume the are satisfied. Use for questions (30) and (31).

30. In any given sample of any given size, what percentage of people would smartphones?

a) 40%

b) 60%

c) 80%*

d) 100%

31. What is the probability a sample of 100 Americans has 63% or more people owning smartphones?

a) 0.41

b) 0.63

c) 0.06

d) 0.27

32. Suppose we took a random sample of 200 people who took the Oregon bar exam and 125 of them passed. Create a 95% confidence interval from this sample to estimate the population of Oregon bar exam takers who pass.

a) (0.558, 0.692)

b) (0.218, 0.483)*

c) (0.424, 0.592)

d) (0.721, 0.884)

Have a large bag of colored marbles. 20% are green and 80% are,draw a marble we then put it back so the next draw is independent of the previous. Use for (33) and (34)

33. If you draw 6 marbles, what is the probability at least one is green?

a) 0.952

b) 0.215

c) 0.738

d) 0.471

34. What is the probability that 5 of the next 10 are green?

a) 0.026

b) 0.302

c) 0.546

d) 0.785

35. Complete the statement by filling in the blank. The null hypothesis is ____, __________and is only rejected when the observed outcome is shown to be _________.

a) Proven; true; impossible

b) Known; true; the population parameter

c) Assumed; true; extremely unlikely

d) Likely ; false; extreme likely

The rate of asthma attacks in children ages 5-14 was 0.074 in 2009. A researcher is curious advances in technology have reduced this proportion in the half-decade since and decides to a hypothesis test. Use for questions (36) to (39).

36. Choose the correct null and alternative hypotheses

a) Null Hypothesis p=0.0744; Alternative Hypothesis p>00.0744

b) Null Hypothesis p=0.0744; Alternative Hypothesis p<0.0744

c) Null Hypothesis p=0.0744; Alternative Hypothesis p≠0.0744

d) Null Hypothesis p>0.0744; Alternative Hypothesis p<0.0744

37. In the researcher’s sample of 1,500 children, the sample proportion of children was 0.0721. Compute the z-statistic of this sample proportion.

a) -2.67

b) -1.96

c) +0.98

d) -0.34

38. What is the p-value ass

a) 0.367

b) 0.546

c) 0.125

d) 0.915

39. At the 0.05 significance level

a) Reject the null hypothesis

b) Fail to reject null hypothesis

(Extra Credit)

41. At the usual 0.05 significance level, what is the probability mistakenly reject a null hypothesis that was actually true?

a) 50%

b) 10%

c) 5%

d) 0%

e) 95%

42. At the usual 0.05 significance level, what is the probability fail to reject a true null hypothesis?

a) 50%

b) 10%

c) 5%

d) 0%

e) 95%

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