When parking a car in a downtown parking lot, drivers pay according to the number of hours or parts thereof. The probability distribution of the number of hours cars are parked has been estimated as follows.

x 1 2 3 4 5 6 7 8 P (x) .24 .18 .13 .10 .07 .04 .04 .20 Find the mean and standard deviation of the number of hours cars are parked in the lot.