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Non-Devore problem: Explain what is wrong with the following argument.
Suppose that X is the height of a randomly chosen person, measured in inches, and Y is the height of that same person, measured in feet. Since 12*Y = X, Var(12*Y-X) = 0. But using the rules for variance, Var(12*Y - X) = 144*Var(Y) + Var(X) > 0. What's wrong?
Problems from Devore: