Example 29: ROLLING TWO DICE We want to define a random variable for the sum of the two numbers on the two dice. Let N = {(w1, w2) | W1, W2, E {1, ..., 6}} and X : N R is such that X (w1, W2) = w1 + W2. Then, the probability of having the number 10 is Px({10}) = = P(X({10})) = P({(w1, W2) N | X(w1, w2) = 10}) P({(4,6)}) + P({(6,4)}) + P({(5,5)}) = 1/12.