A 95 confidence interval for the difference in the population ...

[amal]

A 95 confidence interval for the difference in the population proportions of men (group 1) and women (group 2) who exercise regularly, is -0.06 to +0.10. Which of the following is not a reasonable conclusion from this confidence interval?
 a. It is plausible that men spend 10 more time exercising, on average, than do women.
  b. It is plausible that equal proportions of men and women exercise regularly.
  c. It is plausible that the difference in proportions of men and women who exercise regularly is at least 0.05.
  d. It is not plausible that the difference in proportions of men and women who exercise regularly is at least 0.15.

Question 2

At a small college somewhere on the East coast, 20 of the girls and 30 of the boys smoke at least once a week. Independent random samples of 75 girls and 100 boys are to be selected and the proportions of smokers in the samples are to be calculated. What is the standard deviation of the sampling distribution of the difference in the sample proportion of girl smokers and the sample proportion of boy smokers?

[Jossy]

Answer to Question 1

A

Answer to Question 2

0.0651