6.52 Grandparents Let X = the number of living grandparents that a randomly selected adult American has. According to recent General Social Surveys, its probability distribution is approximately P102 = 0.71, P112 = 0.15, P122 = 0.09, P132 = 0.03, P142 = 0.02.

a. Does this refer to a discrete or a continuous random variable? Why?

b. Show that the probabilities satisfy the two conditions for a probability distribution.

c. Find the mean of this probability distribution.