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
90% = mean ± 1.645 SEm
SEm = SD/√n
I'll let you do the calculations.
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 your 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
.
2 answers
mean=43.49
4 answers