18. In a sample of seven cars, each car was tested for nitrogen-oxide emissions (in grams per mile)
and the following results were obtained: 0.06, 0.11, 0.16, 0.15, 0.14, 0.08, 0.15. Assuming that
this sample is representative of the cars in use, construct a 98% confidence interval estimate of
the mean amount of nitrogen-oxide emissions for all cars. If the EPA requires that nitrogen-oxide
emissions be less than 0.165 g/mi, can we safely conclude that this requirement is being met?
Assume the population is normally distributed.