a. A department will interview 10 candidates for a position, and call back for second interviews those who answer the interview questions to the satisfaction of all the interviewers. They hope to call back at least 3, but past experience suggests an average of about 1 call back per 4 interviews. b. A factory posts on the wall the number of days since its last safety infraction of injury. In the past year, the factory has had a safety infraction or injury on 6 different days. The factory is interested in the n umber of days that can be expected to elapse without an injury. c. Fifteen of a doctor’s patients have the same ailment. Studies have shown that about 86.5% of patients with this ailment respond to a certain drug. The doctor prescribes the drug to all 15, but the number who will respond in this case is, of course, not known in advance.