(a) Find the probability that for a randomly selected office hour, the number of student arrivals is 3.

(a) Find the probability that for a randomly selected office hour, the number of student arrivals is 3. (b) What is the probability that he will get at most 5 students in a randomly selected office hour? (c) What is the probability that he will get 5 students in two office hours? Problem # 8: The owner of a fast-food restaurant has found the daily demand for ground beef at her restaurant to be normally distributed, with a mean of 240 lb and a standard deviation of 23 lb. Since the fast-food business is very competitive, the manager would like to ensure that sufficient ground beef is available in her restaurant each day so that the probability is no greater than 1% that the day"s supply is exhausted. How many pounds of ground beef should the manager have available for use each day? Problem # 9: The times of first failure of a unit of a brand of ink jet printers are approximately normally distributed with a mean of 1,500 hours and a standard deviation of 200 hours. (a) What fractio