Thanks in advance for your help.

5. (10 points) Suppose you arrive at a post office with two clerks at a moment when both are busy but there is no one else waiting in line. You will enter service when either clerk becomes free. If service times for clerk i are exponential with rate di, i = 1, 2, find E{T}, where T is the amount of time that you spend in the post office. (Hint: consider two possible scenarios in which you are served by clerk , i = 1, 2. You can find the answer in the textbook)