At a large university, the graduation rate for the general student body was reported to be 0.66. For two of the following, we cannot use this chapter's methods to find the probability in question; explain why in each case.
a. The probability that at least 2 in a random sample of 4 from the general student body graduate.
b. The probability that at least 64 in a sample of 90 pre-med students graduate.
c. The probability that at least 64 in a random sample of 90 from the general student body graduate.