In a multiple regression, the following sample regression equation is obtained: y-hat = 155 + 11.2x1 + 2.3x2.

a. Predict y if x1 equals 21 and x2 equals 33. (Round your answer to 1 decimal place.)

y-hat =

b. Interpret the slope coefficient of x1.

As x1 increases by one unit, y is predicted to decrease by 11.2 units, holding x2 constant.

As x1 increases by one unit, y is predicted to increase by 2.3 units, holding x2 constant.

As x1 increases by one unit, y is predicted to increase by 11.2 units, holding x2 constant.

As x1 increases by one unit, y is predicted to decrease by 2.3 units, holding x2 constant.