(b) Compute 2, the variance of x. The variance, o, of a probability distribution is used to describe the spread of the values of the random variable. The formula for the variance of a probability distribution is given below. 0 = (x -) f(x) The mean, , is needed to calculate the variance. We found E(x) = = 8. Again, the use of a table will help organize the necessary values to find the variance. X X-F (x-1) f(x) (x-1)f(x) 4 4-8=-4 (-4) = 16 0.25 16(0.25) 8 0 0 0.50 12 4 Thus, the variance is o = 0.25 == 0 = (x-) f(x)