Question: The total sustained load on the concrete footing of a planned building is the sum of the dead load plus the occupancy load. Suppose that the dead load X1 has a gamma distribution with a1 = 50 and ß1 = 2, whereas the occupancy load X2 has a gamma distribution witha2 = 20 andß2 = 2. (Units are in kips.) Assume that X1 and X2 are independent.
a. Find the mean and variance of the total sustained load on the footing.
b. Find a value for the sustained load that will be exceeded with probability less than 1/16.