=+b) Examine the residuals to determine if a linear regression is appropriate.

M15_SHAR8696_03_SE_C15.indd 531 14/07/14 7:30 AM 532 CHAPTER 15 Inference for Regression

c) Test an appropriate hypothesis to determine if the association is significant.

d) What percentage of the variability in unemployment is accounted for by the regression model?

25. Used cars. Classified ads in a newspaper offered several used Toyota Corollas for sale. Listed below are the ages of the cars and the advertised prices.

Age (yr) Prices Advertised ($)

1 13990 1 13495 3 12999 4 9500 4 10495 5 8995 5 9495 6 6999 7 6950 7 7850 8 6999 8 5995 10 4950 10 4495 13 2850