problem 7 Consider a circuit switch serving 100 telephone subscribers. Assume the subseribers' Page 9 of 10 calling patterns are as follows: - 20 users, each one of them makes I call/hour with duration 6 min/call - 40 users, cach makes 9 calls/hour with duration 30 seconds/call - 40 users, each makes 6 calls/hour with duration 1min/call a) Find the total offered traffic load a to the switch (measured in Erlangs) b) Assume you want to design the switch to guarantee at most 1% blocking probability. What should be the number of switch trunks to satisfy this? c) Suppose the subscriber number is doubled (i.e., 200), while still having the same calling pattern. Do you think the number of trunks needed to satisfy the 1% blocking must be exactly doubled? less than doubled?, or more than doubled compared to part b). Give a specific reason, but without detailed computation. Note: you can use the attached Erlang-B figure for your answers