Many colleges and universities hold a “blood drive” for organizations such as the Red Cross. To help with

Question

the planning of an upcoming blood drive, we want to estimate the proportion, p, of students and faculty who
would be willing to donate a pint of blood. The Red Cross would like us to estimate p with 99% confidence
such that the margin of error is no greater than 0.04. How large should the random sample be if
(A) the proportion has always been at most 0.24?
(B) no other information is given?