a. Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (±.005) and its Z score.
99% = mean ± Z (SD) = 34 ± 2.575(12)
b. Z = (score-mean)/SEm
SEm = SD/√n
Use same table to find probability ≤ .01.
The manager of Lone Star Restaurant believes that the average wait time of the Saturday evening meal is 30 minutes. To test this belief, the manager selects 50 customers at random and computes the average wait time to be 34 minutes. Assume a population standard deviation of 12 minutes.
a. Find a 99% confidence interval for the mean wait time of a customer.
b. Do the data indicate that the mean wait time differs from 30 minutes at the 1% significance level?
1 answer
1 answer