A particular branch of a bank has 30 full-time operating staff that includes branch manager, assistant managers, loan officers, clerks and security personnel. Because of the demonetarization issue banks are running 7 days a week and the bank does not have full complement of staff to handle the increased customer crowd.

In addition there are times when staff are absent as they are getting sick because of the increased stress levels. The branch manager conducted an audit to determine if there is any kind of strong relationship between the number of staff absent and the average time that the customer had to stand in the queues inside the bank. The following was his observation from the past 10 days information:

No. of staff absent: 1 3 8 0 4 2 3 5 9 7

Avg. waiting Time (in mins): 5 12 30 6 16 15 20 22 27 24

a) Develop the linear regression equation that best describes the relationship. What is the estimate of the time delay per employee absent?

b) When the bank has full complement of staff, what is the average waiting time in the queue as predicted by the linear regression? If there are six employees absent, estimate the average waiting time as predicted by the linear regression?