(10 points) Ding Dong Canteen reported that the waiting time of customers is normally distributed with a mean of 3 minutes and a standard deviation of 1 minute. The canteen committee wanted to know if the waiting time is longer than 3 minutes or not. They took a random sample of 50 customers and found the mean waiting time to be 2.75 minutes. H0: u S 3 H141 > 3 a. Compute the value of the test statistic. b. At 0.05 signicance level, using the critical value approach, can we conclude that the mean waiting time is less than 3 minutes? (9 points) What are the properties of a good point estimator? Explain briey. (diagrams can help explain.)