Question

The number of domestic and imported retail car sales (in hundreds of thousands) in the United States for a period of 9 years are given in the following table.

Year	Domestic Car Sales	Imported Car Sales
Year 1	69.8	17.2
Year 2	68.3	20.1
Year 3	63.2	21.1
Year 4	58.8	22.4
Year 5	55.3	20.8
Year 6	53.6	21.4
Year 7	54.8	21.9
Year 8	54.4	23.3
Year 9	52.5	23.8

(a) Letting x = the number of domestic car sales and y = the number of imported car sales, plot the data.

Do the data exhibit a linear trend?

YesNo     

(b) Find the line of best fit. (Round your answers to one decimal place.)
ŷ =  x +  

(c) Predict the number of imported car sales when there are 6,000,000 domestic car sales. (Round your answer to one decimal place.)
hundred thousand car sales

(d) Predict the number of domestic car sales when there are 2,300,000 imported car sales. (Round your answer to one decimal place.)
hundred thousand car sales

(e) Find the coefficient of correlation. (Round your answer to three decimal places.)


(f) Are the predictions in parts (c) and (d) reliable? Why or why not?

Yes, they are reliable since the slope is positive.Yes, they are pretty reliable since the correlation coefficient is relatively close to 1.     Yes, they are pretty reliable since the correlation coefficient is relatively close to −1.No, they are not reliable since the slope is negative.No, they are not reliable since the correlation coefficient is close to 0.

Answer 1