According to a survey, 61% of murders committed last year were cleared by arrest or exceptional means. Fifty murders committed last year are randomly selected, and the number cleared by arrest or exceptional means is recorded.
(a) Find the probability that exactly 39 of the murders were cleared.
(b) Find the probability that between 36 and 38 of the murders, inclusive, were cleared.
(c) Would it be unusual if fewer than 20 of the murders were cleared? Why or why not?