Each car in a sample of seven cars was tested for nitrogen-oxide emissions (in grams per mile), and the following results were obtained.

0.04

,

0.13

,

0.17

,

0.13

,

0.12

,

0.07

,

0.13

a. Assuming that this sample is representative of cars in use, construct a 95% confidence interval estimate of the mean amount of nitrogen-oxide emissions for all cars.