STAT Questions

STAT415 Assessment #3 Quiz

You must show all of your work in order to receive full and/or partial credit.

1. (8pts) In samples of graduates, it was found that 35 of 120 men had lived on campus during their entire time as students, and 18 of 60 women had done so. Give a 90% confidence interval for the difference (males minus females) between the proportions living on campus for the populations represented by these samples.

2. A candidate for an upcoming election is expected to capture 70% of the votes. To get a better idea of his chances, his team wants to collect a random sample from the voters and compute a 95% confidence interval for the actual percentage in his favor.

(a) (6pts) What sample size is required to estimate the population percentage in favor if the width of the interval is to be no more than than 5%?

(b) (6pts) Using your sample size above, suppose the observed sample percentage is 60%. Compute and interpret the 95% confidence interval.