Hi
Note: The probability of x successes in n trials is:
P = nCx*where p and q are the probabilities of success and failure
respectively. In this case p = .20 and q = .80
nCx =n =100
probability that between 17% and 22% of 100 randomly selected pregnancies are classified as premature?
P( >22) - P(<17) = .8077 - .1923 = .6154