2. Mean and variance of a discrete random variable This problem follows the example at minute 09:00 of Ch5 part 1 video. The table below contains the track record of supreme court justice nominations by presidents, going as far back as Kennedy Number of justices nominated How many presidents got to nominate that many 1 (Carter) NHO 1 (Ford) 6 (Kennedy, Johnson, both Bushes, Clinton, Obama) 3 1 (Trump) 4 1 (Nixon) (a) Calculate the relative frequencies to map the number of nominations into the probability of observing that many. Show work (b) Find the mean (and thus the expected value) number of nominations. Show work. (c) Find the variance. Show work. Report its units