In Exercise 5-31, the monthly demand for MMR vaccine was assumed to be approximately normally distributed with a mean and standard deviation of 1.1 and 0.3 million doses, respectively. Suppose that the demands for different months are independent, and let Z denote the demand for a year (in millions of does). Determine the following:

(a) Mean, variance, and distribution of Z

(b) P(Z < 13.2)

(c) P(11< Z < 15)

(d) Value for c such that P(Z < c) = 0.99