The Harvard study mentioned in the previous exercise estimated that 19% of college students abstain from drinking alcohol. To estimate this proportion in your school, how large a random sample would you need to estimate it to within 0.05 with probability 0.95, if before conducting the study
a. You are unwilling to predict the proportion value at your school.
b. You use the Harvard study as a guideline.
c. Use the results from parts a and b to explain why strategy (a) is inefficient if you are quite sure you’ll get a sample proportion that is far from 0.50.