3 suppose users share a 1 mbps link also suppose each user requires 10

Question

3. Suppose users share a 1 Mbps link. Also suppose each user requires 100kbps when
transmitting, but each user transmits only 10 percent of the time.
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 40 users. Find the probability that at any given time, exactly n users
are transmitting simultaneously.
4. List five access technologies. Classify each one as residential access, company access or
mobile access.