In a simple linear regression, the following sample regression equation is obtained: yˆ=433−21x. a. Interpret the slope coefficient. As x increases by 1 unit, y is predicted to decrease by 21 units. As x increases by 1 unit, y is predicted to increase by 21 units. As x increases by 1 unit, y is predicted to decrease by 433 units. As x increases by 1 unit, y is predicted to increase by 433 units. b. Predict y if x equals −25.