An engineer is going to redesign an ejection seat for an airplane. The seat was designed for pilots weighing between 120 lb and 171 lb. The new population of pilots has normally distributed weights with a mean of 128lb and a standard deviation of 25.4lb.

a. If a pilot is randomlyselected, find the probability that his weight is between 120 lb and 171 lb.

b. If 34 different pilots are randomlyselected, find the probability that their mean weight is between 120 lb and 171 lb.