The table below shows the distribution of ages of workers in a company.

Age/ yr	17 - 21	22 - 26	27 - 31	32 - 36	37 - 41	42 - 46	47 - 51	52 - 56
Workers	12	24	30	37	45	25	10	7

(a) Using an assumed mean of 39, calculate the (i) mean (ii) standard deviation; of the distribution.

(b) If a worker is selected at random from the company for an award, what is the probability that he is at most 36 years old?