Do lighter cars use less gasoline? To answer this question, a researcher randoml

Question

Do lighter cars use less gasoline? To answer this question, a researcher randomly selected 15 cars. He collected data about the weight (in hundreds of pounds) and the mileage (mpg) for each car. From a scatterplot made with the data, a linear model seems appropriate with r2=0.64

1) The response variable in this study is A) weight B) mileage C) both D) neither E) not enough info

2) The equation of the least-squares regression line is
ˆ y =40.40.521 x

3) Which of the following descriptions of the value of the slope is the correct description? A) The mileage is expected to increase by 0.521 when the weight of a car increases by 1 pound. B) We cannot interpret the slope because we cannot have a negative weight of a car. C) The mileage is expected to decrease by 0.521 when the weight of a car increases by 100 pounds. D) All of the above    E) None of the above

4) The correlation between the weight and mileage is A) -0.521 B) -0.64 C) 0.8 D) -0.8 E) None of the above

44. What will be the slope of the regression line if we try to infer weight from mileage by setting mileage to be the explanatory variable? A) -1.919 B) -0.786 C) -1.228 D) 0.521 E) None of the above

Explanation / Answer

1) The response variable in this study is  B) mileage

3) The mileage is expected to decrease by 0.521 when the weight of a car increases by 100 pounds.

4) The correlation between the weight and mileage is D) -0.8

4.4) slope of the regression line if we try to infer weight from mileage by setting mileage to be the explanatory variable =(-0.8)*(-0.8)/(-0.521)=-1.228 option C

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