Shanta runs an industry in a shed which is in the shape of a cuboid surmounted by a half cylinder (see Fig. 13.12). If the base of the shed is of dimension 7 m x 15 m, and the height of the cuboidal portion is 8m, find the volume of air that the shed can hold. Further, suppose the machinery in the shed occupies a total space of 300 `m^3` and there are 20 workers, each of whom occupy about 0.08 `m^3` space on an average. Then, how much air is in the shed? (Take `pi=22/7`)