The following data (also available from the book€™s website) is from a random sample of campus newspaper ads on used cars for sale. Consider the age and horsepower (HP) of a car to predict its selling price. (The variable Type stands for whether the car is from the United States, coded as 1, or a foreign car, coded as 0. This variable will be considered in exercise 13.48.)
a. Construct a scatterplot matrix (or separate scatterplots) to investigate the relationship among price, age, and horsepower and interpret.
b. Find the multiple regression prediction equation for the selling price in terms of age and horsepower of a car. What is the predicted price for a car that has a horsepower of 80

(i) is 8 years old, 

(ii) 10 years old, rounded to the nearest hundred?
c. Based on this multiple regression, can you predict the price difference between a car with 60 HP and a car with 80 HP without knowing the ages of the two cars? Explain.

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НР Туре Price Age НР Туре Car Price Age HP Type Car 55 1 8700 9. 11 5050 10 44 75 75 11200 12 14800 13 12 55 3 9000 9. 69 1800 76 82 4 10300 10 14 7200 10 15 10500 76 8600 9. 73 1 5250 6. 12 49 16 13000 9. 130 12000 120 17 11790 95 2500 124 11 79 18 12350 90 74 8300 19 6100 10 10 9300 38