1. To calculate the average waiting time for a customer, we first need to find the utilization rate of the on-call lawyer.
Utilization = (average service rate / average arrival rate)
Service Rate = 1 email / 5 minutes = 1 email / (1/12 hours) = 12 emails per hour
Arrival Rate = 10 emails per hour
Utilization = Service Rate / Arrival Rate
Utilization = 12 / 10 = 1.2
The utilization rate suggests that the system is unstable; that is, the number of incoming emails is higher than the service rate. The average waiting time for the customer cannot be determined in this case.
2. The amount of time a lawyer can dedicate to pursuing high-value cases depends on the time spent on responding to emails. During a 10-hour shift, there are 600 minutes. Since the average writing time is 5 minutes, and the arrival rate is 10 emails per hour:
Total email writing time = 10 emails per hour * 5 minutes per email * 10 hours = 500 minutes
Time available for high-value cases = 600 minutes - 500 minutes = 100 minutes
3. To determine how the new policy would affect the time available for high-value cases, we must first find the new utilization rate:
New Standard Deviation = 0.5 minutes
Coefficient of Variation (CV) = Standard Deviation / Mean
New CV = 0.5 / 5 = 0.1
Utilization after the new policy = (12 * New CV^2) / (10 * Old CV^2)
Utilization = (12 * 0.1^2) / (10 * 1^2) = 0.12
Now we can calculate the average waiting time using Pollaczek-Khintchine Formula:
Average Waiting Time = (Mean Service Time * Utilization^2) / (2 * (1 - Utilization))
= (5 * (0.12^2)) / (2 * (1- 0.12)) = 0.41394 minutes
Now, we can calculate the time spent on email writing and subtract it from the total available time during the shift.
Total email writing time = (5 minutes + 0.41394 minutes) * 10 emails per hour * 10 hours = 541.394 minutes
Time available for high-value cases = 600 minutes - 541.394 minutes = 58.606 minutes
So, under the new policy, a My-law lawyer would have approximately 58.61 minutes to pursue high-value cases during a 10-hour shift.