Show that, for a binomial random variable, E[Y(Y - 1)] = NPQ + 2 - .

Show that, for a binomial random variable, E[Y(Y - 1)] = NPQ + μ² - μ. write the expected value as a sum, factor out y(y - 1), and then factor terms until each term in the sum is a binomial probability. Use the fact that ∑_y p(y) = 1 to sum the series.