1. Packet switching vs. circuit switching. The following figure shows that many users are sharing a 1Mbps access link to the Internet. Suppose each user is either in active status that required data access rate of 120kbps, or in idle status that the user requires no data. Each user is active only 8% of the time, and users are independent with each other in their activities. N users 1 Mbps link a). If circuit switching is used, how many users can this access link support (meaning that every user allowed in this network should be able to get his/her required bandwidth)? b). If packet switching is used and there are 10 users. How often is this access link idle? How often does this link serve just 1 user? c). If packet switching is used and there are 40 users, how often does the access link be congested? (Hint: the link is congested if and only if all active users' combined required bandwidth is over the 1Mbps link capacity). Note: for question c), if you cannot generate a numeric value, it is OK to provide your answers as a series of expressions. But please show your deriving process as much as possible