4. [20 pts] Suppose users share a 2 Mbps link. Also suppose each user requires 200 kbps when transmitting, but each user transmits only 15 percent of the time. (See the discussion of statistical multiplexing in Section 1.3.) (a) When circuit switching is used, how many users can be supported? (b) For the remainder of this problem, suppose packet switching is used. Find the probability that a given user is transmitting. (c) Suppose there are 50 users. Find the probability that at any given time, exactly n users are transmitting simultaneously. (Hint: Use the binomial distribution.) (d) Find the probability that there are 15 or more users transmitting simultaneously. 4. [20 pts] Suppose users share a 2 Mbps link. Also suppose each user requires 200 kbps when transmitting, but each user transmits only 15 percent of the time. (See the discussion of statistical multiplexing in Section 1.3.) (a) When circuit switching is used, how many users can be supported? (b) For the remainder of this problem, suppose packet switching is used. Find the probability that a given user is transmitting. (c) Suppose there are 50 users. Find the probability that at any given time, exactly n users are transmitting simultaneously. (Hint: Use the binomial distribution.) (d) Find the probability that there are 15 or more users transmitting simultaneously