Transformations and Covariance Formula Sheet

Y=aX+b
E(Y)=aE(X)+b
Var(Y)=a^2Var(X)
SD(Y)=|a|SD(X)
E(X+Y)=E(X)+E(Y)
Var(X+Y)=Var(X)+Var(Y)+2Cov(X,Y)
Under independence Cov(X,Y)=0. Never add standard deviations directly.

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