Question

For a sample of nine automobiles, the mileage (in 1000s of miles) at which the original front brake pads were worn to 10% of their original thickness was measured, as was the mileage at which the original rear brake pads were worn to 10% of their original thickness. The results are given in the following table.

Automobile	Front	Rear
1	32.8	40.5
2	26.6	35.2
3	35.6	46.1
4	36.4	46
5	29.2	39.9
6	40.9	51.7
7	40.9	51.6
8	34.8	46.1
9	36.6	47.3

Let μXμX represent the population mean for rear brake pads and let μYμY represent the population mean for front brake pads. Find a 95% confidence interval for the difference μD=μX−μYμD=μX−μY. Round the answers to three decimal places.

The 95% confidence interval for the difference in mean is (_,_ ).

Answer 1

The statistical software output for this problem is :

The 95% confidence interval for the difference in mean is : (4.922 , 15.211)