The manager of the Cottonwood Grille recently selected a random sample of 18 customers and kept track of how long the customers were required to wait from the time they arrived at the restaurant until they were actually served dinner. This study resulted from several complaints the manager had received from customers saying that their wait time was unduly long and that it appeared that the objective was to keep people waiting in the lounge for as long as possible to increase the lounge business. The following data were recorded, with time measured in minutes:

a. Compute the mean waiting time for this sample of customers.
b. Compute the median waiting time for this sample of customers.
c. Compute the variance and standard deviation of waiting time for this sample of customers.
d. Develop a frequency distribution using six classes, each with a class width of 10. Make the lower limit of the first class 15.
e. Develop a frequency histogram for the frequency distribution.
f. Construct a box and whisker plot of these data.
g. The manager is considering giving a complementary drink to customers whose waiting time is longer than the third quartile. Determine the minimum number of minutes a customer would have to wait in order to receive a complementary drink.