Suppose a 2 Mbps link is available where each user alternates between activity (users generate data at a constant rate of 200kbps) and a period of inactivity (user generates no data) where each user is active 10% of the time (20 pts)

1. a. When circuit switching is used, how many users can be supported? 
2. b. When packet switching is used, find the probability that a given user is transmitting.
3. c. Suppose there are 40 users. Find the probability that at any given time; exactly n users are transmitting simultaneously. 
4. d. Find the probability that there are n or more users transmitting simultaneously.