The following regression model has been proposed to predict

The following regression model has been proposed to predict monthly sales at a shoe store, y = 40 - 3x_1 + 12x_2 + 10x_3 where x_1 = competitor\'s previous month\'s sales (in $ 1,000s) x_2 = Stores previous month\'s sales (in $ 1,000s) x_3 {1 if radio advertising was used 0 if otherwise y = sales (in $1000s) Predict sales (in dollars) for the shoe store if the competitor\'s previous month\'s sales were $9,000, the store\'s previous month\'s sales were $30,000, and no radio advertisements were run. Predict sales (in dollars) for the shoe store if the competitor\'s previous month\'s sales were $9,000, the store\'s previous month\'s sales were $30,000, and 10 radio advertisements were run.

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