# Regression Practice Problems Not Using Excel

Step by step, please show all work.

21) For n = 6 data points, the following quantities have been calculated:

3xy = 400 3x = 40 3y = 76 3x^2 = 346 3y^2 = 1160

(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) Compared the width of the confidence interval obtained in part (c) with that obtained in part (d). Which is wider and why?

https://brainmass.com/statistics/regression-analysis/regression-practice-problems-not-using-excel-194835

#### Solution Summary

This solution shows step-by-step calculations to determine the least squares regression line, standard error of estimate, confidence intervals and also briefly explains the difference in confidence interval widths.

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