The following table gives information on the limited tread warranties (in thousands of miles) and the prices of 12 randomly selected tires at a national tire retailer as of July 2012.

a. Taking warranty length as an independent variable and price per tire as a dependent variable, compute SSxx, SSyy, and SSxy.
b. Find the regression of price per tire on warranty length.
c. Briefly explain the meaning of the values of a and b calculated in part b.
d. Calculate r and r2 and explain what they mean.
e. Plot the scatter diagram and the regression line.
f. Predict the price of a tire with a warranty length of 73,000 miles.
g. Compute the standard deviation of errors.
h. Construct a 95% confidence interval for B.
i. Test at a 5% significance level if B is positive.
j. Using α = .025, can you conclude that the linear correlation coefficient is positive?

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Warranty (thousands of miles) 60 70 75 50 80 55 65 65 70 65 60 65 Price per tire (S) 95 135 94 90 12 70 140 80 92 125 60 155