What is the primary difference between Backup Speed and Restore Speed?

Q20;

Design and performance of a Call Center. In a call center there are M customer service representatives. Arriving calls are sent to an idle customer service representative. If all customer service representatives are busy then the customer hears a message that “all customer service representatives are currently busy please wait for the next available customer service representative”. These calls are queued up waiting for a free customer service representative. You are to decide how many customer service representatives to hire. Past experience indicates that the customer service representative takes on average 17 min to complete a customer call and calls arrive at a rate of 1 call/min. You need to hire enough customer service representatives (M) to keep the probability of getting the please wait message to less 1% (10-2).

a) Find M.

b) For the load used in part a), plot logo[probability of getting the please wait message] vs M for M=20…50. Comment on the shape of this curve.