Shanta runs an industry in a shed which is in the shape of a cuboid surmounted by a half cylinder. If the base of the shed is of dimension `7m "x"15 m` , and the height of the cuboidal portion is 8 m, find the volume of the air that the shed can hold. If the industry requires machinery which would occupy a total space of `300 m^3` , and there are 20 workers each of whom would occupy `0.08 m^3` space on an average, how much air would be in the shed when it is working. (Take `π= 22/7` ​ )