A random sample of state gasoline taxes in cents is shown here for 12 states. Use the data to estimate the true population mean gasoline tax with 90% confidence. Does you interval contain the national average of 44.7 cents?

38.4 40.9 67 32.5 51.5 43.4
38 43.4 50.7 35.4 39.3 41.4

4 answers

Formula:

CI90 = mean + or - 1.645(sd/√n)

You will need to calculate mean and standard deviation from the data given. Sample size (n) = 12.

Plug values into the formula and compute the confidence interval.

I'll let you take it from here.

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