With individual lines at its various windows, the Humber Valley Credit Union found that the standard deviation for normally distributed waiting times on Friday afternoons was 6.2 min. The credit union experimented with a single main waiting line and found that for a random sample of 25 customers, the waiting times have a standard deviation of 3.8 min. On the basis of previous studies, we can assume that the waiting times are normally distributed. Use a 0.05 significance level to test the claim that a single line causes lower variation among the waiting times. Why would customers prefer waiting times with less variation? Does the use of a single line result in a shorter wait?
Use the traditional method to test the given hypotheses. Follow the steps outlined and draw the appropriate graph. In all cases, assume that the population is normally distributed and that the sample has been randomly selected.