With individual lines at the checkouts, a store manager finds that the standard deviation for the waiting times on monday mornings is 5.2 minutes. after switching to a single waiting line, he finds that for a random sample of 29 customers, the waiting times have a standard deviation of 4.3 minutes. assume that line waiting times on mondays are normally distributed. use a 0.05 significance level to test whether the standard deviation of the waiting times using a single line differs from 5.2 minutes.