3. Research has shown that the weights of males are normally distributed with a mean of 189 lb. and a standard deviation of 39 lb. a) What is the probability that a single man, chosen at random will have a weight greater than 200 lbs.? b) What is the probability that if 15 men get on an elevator that their combined weight is greater than 3000 lbs.? That is, what is the probability that the average weight of these 15 men is greater than 200 lbs