A Multiple Regression Model Has the Form $\hat { Y } = 10 - 4 x _ { 1 } + 3 x _ { 2 }$

Multiple Choice

A multiple regression model has the form $\hat { Y } = 10 - 4 x _ { 1 } + 3 x _ { 2 }$ , where the dependent variable Y represents (in $1,000) , $x _ { 1 }$ represents unit price (in dollars) , and $x _ { 2 }$ represents advertisement (in dollars) . As $x _ { 1 }$ increases by $1, while holding $x _ { 2 }$ fixed, then sales are expected to

A) increase by $7
B) increase by $13
C) decrease by $4
D) decrease by $4,000
E) remain the same