Question

The waiting time to check out of a supermarket has had a population mean of 9.17 minutes.​ Recently, in an effort to reduce the waiting​ time, the supermarket has experimented with a system in which there is a single waiting line with multiple checkout servers. A sample of 50 customers was​ selected, and their mean waiting time to check out was 7.31 minutes with a sample standard deviation of 4.3 minutes.

At the 0.01 level of​ significance, using the critical value approach to hypothesis​ testing, is there evidence that the population mean waiting time to check out is less than 9.17 ​minutes?

What is the test statistics for this test?

(Round your answer to four decimal places)

Answer 1

test statitics:

xbar = 7.31 , sigma = 4.3 , n = 50 , mu = 9.17

t = (xbar - mu)/(sigma/sqrt(n))
= ( 7.31 - 9.17)/(4.3/sqrt(50))
= -3.0586