9．nsider the regression results from the regression of Y against X for 50 observations:

Y = 5.0 + 1.5 X

The standard error of the coefficient is 0.50 and the standard error of the forecast is 0.52. The 95 percent confidence interval for the predicted value of Y if X is 10 is:

A)   {18.980 < Y < 21.019}.

B)   {19.480 < Y < 20.052}.

C)   {19.500 < Y < 20.500}.

D)   {18.954 < Y < 21.046}.

The correct answer was D)

The predicted value of Y is: Y = 5.0 + [1.5 (10)] = 5.0 + 15 = 20. The confidence interval is 20 ± 2.011 (0.52) or {18.954 < Y < 21.046}.