A regression line is given by ŷ = 12 + 3.5x. Predict y when x = 8.

Step 1: Write the regression equation.

The regression line is:
ŷ = 12 + 3.5x

The symbol ŷ represents the predicted value of y.

Step 2: Substitute x = 8.

ŷ = 12 + 3.5(8)

Step 3: Multiply.

3.5(8) = 28

So:
ŷ = 12 + 28

Step 4: Add.

ŷ = 40

Therefore, when x = 8, the regression model predicts y = 40.