In a Random Sample of Patient Records in Cutter Memorial

Multiple Choice

In a random sample of patient records in Cutter Memorial Hospital, six-month postoperative exams were given in 90 out of 200 prostatectomy patients, while in Paymor Hospital such exams were given in 110 out of 200 cases. In comparing these two proportions, normality of the difference may be assumed because:

A) the populations are large enough to be assumed normal.
B) the probability of success can reasonably be assumed constant.
C) the samples are random, so the proportions are unbiased estimates.
D) nπ ≥ 10 and n(1 - π) ≥ 10 for each sample taken separately.