The number of ships to arrive at a harbor on any given day is a random variable represented by x. The probability distribution of x is as follows. (Give your answers correct to two decimal places.)

x 10 11 12 13 14
P(x) 0.38 0.1 0.07 0.12 0.33

(a) Find the mean of the number of ships that arrive at a harbor on a given day.
(b) Find the standard deviation, ó, of the number of ships that arrive at a harbor on a given day.