5. For n = 6 data points, the following quantities have been calculated. x = 40, y = 76, xy = 400, x2 = 346, y2 = 1160, (y y-hat)2 = 52.334,. a) Determine the least-squares regression line b) Determine the standard error of estimate. c) Construct the 95% confidence interval for the mean of y when x = 7.0. d) Construct the 95% confidence interval for the mean of y when x = 9.0. e) Compare the width of the confidence interval obtained in part c) with that obtained in part d). Which is wider and why?