Can you help me with b?

An engineer is going to redesign an ejection seat for an airplane. The seat was designed for pilots weighing between 140 lb and 201 lb. The new population of pilots has normally distributed weights with a mean of 147 lb and a standard deviation of 32.9 lb. a. If a pilot is randomly selected, nd the probability that his weight is between 140 lb and 201 lb. The probability is approximately 0.5327 . (Round to four decimal places as needed.) b. If 31 different pilots are randomly selected, nd the probability that their mean weight is between 140 lb and 201 lb. The probability is approximately D. (Round to four decimal places as needed.)