Example 2 Denote X1,X2 as the score for verbal and quantitative respectively, then var(X1 +X2)=var(X1)+var(X2)+2cov(X1,X2) =64+81+2×0.5×V64×V81 =217 8Example 2 • Denote 𝑋1 , 𝑋2 as the score for verbal and quantitative respectively, then var 𝑋1 + 𝑋2 = var 𝑋1 + var 𝑋2 + 2cov 𝑋1 , 𝑋2 = 64 + 81 + 2 × 0.5 × 64 × 81 = 217 8