Example 4. The manager of a furniture store tells customers that a special order will take six weeks (42 days). During recent months, the owner has received several complaints that the special orders are taking longer than 42 days. A sample of 12 special orders delivered in the last month showed the mean waiting time was 51 days with a standard deviation of 8 days. At 0.05 significance level, are the customers waiting an average of more than 42 days