The following regression model has been proposed to predict sales at a computer store. E(Y) = 50 - 3X_1 + 20X_2 + 10X_3 where X_1 = competitor's previous day's sales (in $1,000s) X_2 = population within 1 mile (in 1,000s) X_3 = {1 if radio advertising was used 0 if otherwise E(Y) = sales (in $1000s) Predict sales (in dollars) for a store with the competitor's previous day's sale of $5,000, a population of 20,000 within 1 mile, and nine radio advertisements. $445,000 $440, 050 $385, 059 $475