The amount of time that sales managers devote to their jobs per week is normally distributed with a mean of 55 hours and a standard deviation of 5 hours. What is the probability that 30 randomly...

The amount of time that sales managers devote to their jobs per week is normally distributed with a mean of 55 hours and a standard deviation of 5 hours. What is the probability that 30 randomly selected sales manager works for

(a) more than 56 hours per week?

(b) between 52 and 56 hours per week?