We're trying to show that the true proportion of women who exercise regularly is greater than that of men. Would this be an example of interval or point estimation?

a Point

b Interval

We're trying to show that the true percent of people who had twins is less than 20%. Which test should we use?

a t-test

b z-test

c confidence interval for

d confidence interval for P

As confidence level increases, a confidence interval

a gets wider

b gets shorter

c doesn't change