# Question: Refer to the data of Exercise 11 9 a Use the regression

Refer to the data of Exercise 11.9.

a. Use the regression line of Exercise 11.10 to calculate predicted values for x 5 60, 80, 100, 120, and 140.

b. For which x- values are most of the actual y- values larger than the predicted y- values? For which x- values are most of the actual y- values smaller than the predicted y- values? What does this pattern indicate about whether there is a linear relation between the drill speed and the lifetime of the bit?

c. Suggest a transformation of the data to obtain a linear relation between the lifetime of the bit and the transformed values of the drill speed.

In exercise

a. Use the regression line of Exercise 11.10 to calculate predicted values for x 5 60, 80, 100, 120, and 140.

b. For which x- values are most of the actual y- values larger than the predicted y- values? For which x- values are most of the actual y- values smaller than the predicted y- values? What does this pattern indicate about whether there is a linear relation between the drill speed and the lifetime of the bit?

c. Suggest a transformation of the data to obtain a linear relation between the lifetime of the bit and the transformed values of the drill speed.

In exercise

## Answer to relevant Questions

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