A random sample of state gasoline taxes is shown for 12 states. Use the data to estimate the true population mean gasoline tax with 90% confidence. Does your interval contain the national average of 0.21? assume normal distribution.

Answer 1

Lacking sample data.

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (±.05) to get the Z score.

90% = mean ± 1.645 SEm

SEm = SD/√n