Question

1) You wonder whether men or women are more likely to be driving when both a man and a woman are in the front seat of a car. You observe 20 cars with both a man and a woman in the front seat and count how many times the man is driving. Of the 20 cars you observed, the man was driving in 15 of them.

What is the probability value for this result? (Give your answer to at least 3 places past the decimal point)

Selected Answer: 2.24

Response Feedback: Incorrect, Review Chapter 11, the Logic of Hypothesis Testing Note that you will need to use Excel or the binomial calculator for this problem http://onlinestatbook.com/2/java/binomialProb.html Note that this is a 2-tailed test because you asked whether men or women were more likely to be driving. Make sure you include both tails.

1a) A professor believes there is a correlation between the amount of hours people are exposed to sunlight and their vitamin D level. He collects a random sample of people and measures their sun exposure and vitamin D levels. The correlation between the two in his sample is .65. The p-value is 0.002. What is the appropriate conclusion?

Selected Answer: There is a relationship between sun exposure and Vitamin D in the population. People who get more sun have lower Vitamin D levels. Answer Feedback: Note the direction of the sample correlation. Response Feedback: Incorrect, Review Chapter 11, the Logic of Hypothesis Testing

Answer 1

1) You wonder whether men or women are more likely to be driving when both a man and a woman are in the front seat of a car. You observe 20 cars with both a man and a woman in the front seat and count how many times the man is driving. Of the 20 cars you observed, the man was driving in 15 of them.

What is the probability value for this result?

Assume that men and women are equally likely to drive

The population proportion of success is p = 0.5 , also, 1 - p = 1 - 0.5 = 0.5 , and the sample size is n= 20n . We need to compute Pr(X=15)

This implies that

1a) A professor believes there is a correlation between the amount of hours people are exposed to sunlight and their vitamin D level. He collects a random sample of people and measures their sun exposure and vitamin D levels. The correlation between the two in his sample is .65. The p-value is 0.002. What is the appropriate conclusion?

There is a relationship between sun exposure and Vitamin D in the population. People who get more sun can have higher or lower Vitamin D levels than the rest of the population ( As the test is two tailed we cannot claim the direction of the correlation )