The probability distribution function for the discrete random variable where x is equal to the number of red lights drivers typically run in a year is as follows. x 0 1 2 3 p(x) 0.76 0.15 0.05 (a) Fill in the missing probability. x 0 1 2 3 p(x) 0.76 0.15 0.05 (b) What is the mean of this discrete random variable