The following table shows the joint probability distribution of random variables Y and X. share of Y X population 0 0 0.15 0 1 0.25 1 0 0.05 1 1 0.55 Answer the following questions: (1 point) a. What is the expected value of X in the population? (2 points) b. What is the expected value of Y conditional on X being equal to zero, E[Y|X=0]?