QUESTION 17

Two major automobile manufacturers have produced compact cars with engines of the same size. We are interested in determining whether or not there is a significant difference in the mean MPG (miles per gallon) when testing for the fuel efficiency of these two brands of automobiles. A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance. The following data (in miles per gallon) show the results of the test. Assume the population of differences is normally distributed.

Driver	Manufacturer A	Manufacturer B
1	33	27
2	28	21
3	27	26
4	27	23
5	26	23
6	30	24
7	32	27
8	26	26

Find the mean of the differences.

3

3.5

4

4.5

QUESTION 18

Two major automobile manufacturers have produced compact cars with engines of the same size. We are interested in determining whether or not there is a significant difference in the mean MPG (miles per gallon) when testing for the fuel efficiency of these two brands of automobiles. A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance. The following data (in miles per gallon) show the results of the test. Assume the population of differences is normally distributed.

Driver	Manufacturer A	Manufacturer B
1	33	27
2	28	28
3	27	25
4	27	24
5	26	24
6	30	27
7	32	22
8	26	28

The mean of the differences is 3. Find the test statistic.

0.819

2.316

2.475

3.665