(ii) The PMF of a random variable X is X 1 2 3 4 p(x) 0.2 0.4 0.3 0.1 Find the CDF of X.MATHnBo - EXERCISE SHEET 3 (iii) Consider whether the next person buying a com puter at a certain electronics store buys a laptop or a desktop model. Let X = 1 if they buy a desktop and X = I] if they buy a laptop. If 20% of all pur chasers during that week select a desktop. Find the PMF and CDF for X