An investigater wants to estimate caffeinne intake in high school students, how many students would be required to ensure that a 95%confidence interval for the mean cofee intake (measure in mg) is within 15mg of the true mean? Assume the standard deviation in coffee intake is 68mg.
Hom many students whould be required to estimate the proportion of students who consume coffee? Suppose we want the estimate to be within 5 percentage points of the true proportion with 95% confidence?