A random variable Y has a probability distribution with possible values of -1, 0, 1, 2 and probabilities of 3C, 2C, 0.4, 0.1 respectively. The question is to find the value of the constant C so that the probabilities sum to 1. The solution shows that for C = 0.1, the probabilities sum to 1, so the value of C is 0.1.