Discrete Random Variable Summary Measures Expected Value of a discrete distribution (Weighted Average) N H=EX)=∑XP(X) X P(X) Example:Toss 2 coins, 0 .25 X=#of heads, .50 compute expected value of X: .25 E(X)=(0x.25)+(1×.50)+(2x.25) =1.0 Chap 5-8 Tongji University School of Economics Management Statistics for Managers Using Microsoft Excel Statistics for Managers Using Microsoft Excel Chap 5-8 Tongji University School of Economics & Management Discrete Random Variable Summary Measures ▪ Expected Value of a discrete distribution (Weighted Average) ▪ Example: Toss 2 coins, X = # of heads, compute expected value of X: E(X) = (0 x .25) + (1 x .50) + (2 x .25) = 1.0 X P(X) 0 .25 1 .50 2 .25 =  = = N i 1 i i E(X) X P(X )