The Department of Motor Vehicles receives complaints about customers having to wait too long at their offices.They collect data and find the average wait time is 35 minutes with a standard deviation of 10 minutes.Assume that wait times are Normally distributed.

a) Find the probability that a randomly selected customer has to wait less than 30 minutes.

b) Find the probability that an SRS of 40 customers has a mean weight time less than 30 minutes.