An certain brand of upright freezer is available in three different rated capacities: 16 ft3, 18 ft3, and 20 ft3. let x = the rated capacity of a freezer of this brand sold at a certain store. suppose that x has the following pmf. x 16 18 20 p(x) 0.1 0.3 0.6 (a) compute e(x), e(x2), and v(x).