Find the mean and variance for the following discrete distributions: (a) f(x) = 1/5, x = 5, 10, 15, 20, 25. z.o.w. (b) f(x) = 1, x = 5.z.o.w (c) f(x) = (4 - x)/6, x = 1, 2, 3. z.o.w.