List of Formulas Sample standard deviation: S= Es. (x , - 3 ) Ef. (m, - x ) or S= n-1 n -1 k The kth percentile: i = (n + 1) 100 Multiplication rule: P(AnB) = P(A| B) P(B) Addition rule: P(AUB) = P(A) + P(B) - P(AnB) Independence test: P(AnB) = P(A)P(B) or P(A| B) = P(A) n! Binomial distribution: n p(x) = "- where n x X x!(n-x)! Mean E(X) = M = np Variance V(X) = 0 = npq Poisson distribution: p ( x ) = eux x! Mean E(X) = U Variance V(X) = 0 = /