Question 10.77

10.77 Predicting college debt.

Refer to Exercise 10.75. Figure 10.21 contains Minitab output for the simple linear regression of AvgDebt on InCostAid.

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  1. State the least-squares regression line.
  2. The University of Oklahoma is one school in this sample. It has an in-state cost of $12,960 and average debt of $26,005. What is the residual?
  3. Construct a 95% confidence interval for the slope. What does this interval tell you about the change in average debt for a change in the in-state cost?

10.77

(a) . (b) . (c) The interval is (0.3473, 0.9567). For each $1000 of in-state cost, we expect on average an average debt of between $347 and $957 at graduation with 95% confidence.