The average electric bill in a residential area is $156 for…

The average electric bill in a residential area is $156 for the month of April.  The standard deviation is $14.  If the amounts of the electric bills are normally distributed, and 25 residents are selected at random, find the probability that the mean of the bill for the 25 residents is:a)  Less than $162 _______ b)  Between $148 and $153 _______