Five automobiles of the same type are to be driven on a 300- mile trip. The first two will use an economy brand of gaso- line, and the other three will use a name brand. Let X1, X2, X3, X4, and X; be the observed fuel efficiencies (mpg) for the five cars. Suppose these variables are independent and nor- mally distributed with = 20, z==s=21, and 24 for the economy brand and 3.5 for the name brand. Define an rv Y by Y X+XX+X4 + Xs 2 3 so that Y is a measure of the difference in efficiency between economy gas and name-brand gas. Compute P(0Y) and P(-1Y 1). [Hint: YaX+.. + asxs, with

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