In a sample of seven cars, each car was tested for nitrogen-oxide emissions (in grams per mile) and the following results were obtained:0.18, 0.12, 0.05, 0.19, 0.18,0.13, 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?

I don't need the answer, I just need to know how to do the steps to get to the answer. This is my last class and I hopefully graduate. This class is extremely hard because I never took anything beyond basic math

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1. Find the mean first = sum of scores/number of scores

Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.

Standard deviation = square root of variance

SEm = SD/√n

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.01) and its Z score.

98% = mean ± Z SEm

98% = mean ± 2.333 SEm

I hope this helps.

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