With individual lines at its various windows, a bank finds that the mean waiting time and the standard deviation for normally distributed waiting times on Monday mornings is 28 minutes and 6.2 minutes, respectively. The bank experiment with a single main waiting line and finds that for a random sample of 25 customers, the waiting times have a mean of 26.7 minutes. Test the claim that a single line causes lower mean waiting time among the waiting lines.

a) Is this a one-tailed or two-tailed test?

b) What test statistic is to be used?

c) What is the decision rule?

d) What is the computed value of the test statistic?

e) What is your decision/conclusion regarding the null hypothesis?