The following data are measures of 81 different SUV models v

The following data are measures of 81 different SUV models vehicles. Included are the average gas mileage in miles per gallon (Avg. MPG) and the engine size in liters (Engine Size). The average miles per gallon is a weighted average of city and highway driving to reflect a 40/60 percent split. Below is the JMP Regression output for a regression of Avg. MPG on Engine Size.

Linear Fit

Avg MPG = 27.653722 - 2.1137404*Engine Size

Summary of Fit

RSquare

0.4615

RSquare Adj

0.4547

Root Mean Square Error

2.6950

Mean of Response

19.8642

Observations (or Sum Wgts)

81.0000

Analysis of Variance

Source

DF

Sum of Squares

Mean Square

F Ratio

Model

1

491.747

491.747

67.7078

Error

79

573.759

7.263

Prob > F

C. Total

80

1065.506

<.0001*

Parameter Estimates

Term

Estimate

Std Error

t Ratio

Prob>|t|

Intercept

27.654

0.993

27.85

<.0001*

Engine Size

-2.114

0.257

-8.23

<.0001*

Based on the regression results and a value for engine size of 3.5 liters, what can we say about the relationship between Avg. MPG when Engine Size?

All are correct

Avg MPG = 27.654+(-2.114*3.5)

Avg MPG = 20.255

R-squared for the regression model is

Based on the regression model, the estimated value of Avg. MPG when Engine Size is 1.5 liters is:

27.654+(-2.114*1.5)

27.654+(-2.114*2)

1.5*-2.114

27.654*2 +(-2.114)

RSquare	0.4615
RSquare Adj	0.4547
Root Mean Square Error	2.6950
Mean of Response	19.8642
Observations (or Sum Wgts)	81.0000

Solution

1.

D.The larger the engine size the lower the average MPG. [ANSWER, because the coefficient for engine size is -2.114 is negative.]

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2.

B..4615 [ANSWER, given]

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3.

A. 27.654+(-2.114*1.5) [we just substitute 1.5 to engine size)

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