Roger Gallagher owns a used car lot that deals solely in used Corvettes. He wants to develop a regression model to help predict the price he can expect to receive for the cars he owns. He collected the data found in table below describing the mileage, model year, presence of a T-top, and selling price of a number of cars he has sold in recent months. Let Y represent the selling price,

X₁

the mileage (in thousands of miles),

X₂

the model year, and

X₃

the presence (or absence) of a T-top.

Mileage (in thousands of miles)	Year	T-top	Price (in dollars)
115	1968	1	$14,075
95	1970	0	$11,200
125	1972	0	$8,200
85	1974	0	$15,150
77	1976	1	$15,825
105	1978	0	$11,500
90	1979	0	$13,450
71	1981	1	$16,700
55	1983	0	$16,700
65	1987	1	$19,700
45	1988	0	$22,500
15	1988	0	$25,700
23	1991	1	$32,100

(B)

Determine the parameter estimates for the regression function represented by:

_i = b₀ + b₁X_1i + b₂X_2i

What is the estimated regression function? (Use X₁ for X_1i and X₂ forX_2i. Round your numerical values to one decimal place.)

_i =???

(C) Use the binary variable X_3i to indicate whether or not each car in the sample has a T-top ( X_3i = 0 indicates a car does not have a T-Top, X_3i = 1 indicates a car has a T-Top). Determine the parameter estimates for the regression function represented by:

_i = b₀ + b₁X_1i + b₃X_3i

According to the previous model, on average, how much does a T-top add to the value of a car (in dollars)? (Round your answer to the nearest dollar.)

$=???

Determine the parameter estimates for the regression function represented by:

_i = b₀ + b₁X_1i + b₂X_2i + b₃X_3i

What is the estimated regression function? (Use X₁ for X_1i, X₂ for X_2i, and X₃ for X_3i. (Round your numerical values to one decimal place.)

_i =???