Let a pair of dice be thrown and random variable X be the sum of the numbers that appear on the two dice. Following is the probability distribution of X given for you. Find the mean of X.

7

Mean : E(X) = (2)(1/36) + (3)(2/36) + (4)(3/36) + (5)(4/36) + (6)(5/36) + (7)(6/36) + (8)(5/36) + (9)(4/36) + (10)(3/36) + (11)(2/36) + (12)(1/36)

                  = 252/36

                  = 7