In a multiple linear regression with 40 observations, the following sample regression equation is obtained: y = 12.8 + 2.6x1 - 1.2x2 With se = 5.84. Also, when x1 equals 15 and x2 equals 6, se (y ) = 2.20. (You may find it useful to reference the t table.) a. Construct the 95% confidence interval for E() if x1 equals 15 and *2 equals 6. (Round your final answers to 2 decimal places.) Confidence interval 32.77 to 56.43 b. Construct the 95% prediction interval for y if x1 equals 15 and x2 equals 6. (Round your final answers to 2 decimal places.) Prediction interval 40.14 to 49.06 c. Which interval is wider? O Confidence interval since it does not include the variability caused by the error term. O Prediction interval since it does not include the variability caused by the error term. O Prediction interval since it includes the variability caused by the error term. O Confidence interval since it includes the variability caused by the error term