Chapter 13.3, Problem 22PB

Variability in college GPA Refer to the previous two exercises.

1. a. Report the residual standard deviation. What does this describe?
2. b. Interpret the residual standard deviation by predicting where approximately 95% of the Georgia college GPAs fall when high school GPA = 3.80 and study time = 5.0 hours per day, which are the sample means.

13.20 Predicting GPA For the 59 observations in the Georgia Student Survey data file on the book’s website, the result of regressing college GPA on high school GPA and study time follows.

Regression Equation

CGPA = 1.126 + 0.643 HSGPA + 0.0078 Studytime

Coefficients

1. a. Explain in nontechnical terms what it means if the population slope coefficient for high school GPA equals 0.
2. b. Show all steps for testing the hypothesis that this slope equals 0.