(2pts * 8) Suppose there is a population with 20 short people and 60 tall people. You randomly sample one person. If the sampled person is short, record X = 0 and then flip a coin. Then, if the coin comes up heads, record Y = 0; if the coin comes up tails, record Y = 1. If the sampled person is tall, record X = 1 and Y = 0. (That is, if the person selected is tall, you do not flip a coin.) a. What is the joint p.m.f. of X and Y? b. What is the marginal p.m.f. of X? c. What is the conditional p.m.f. of Y given X = 0? d. What is the conditional p.m.f. of Y given X = 1