1. System A consists of a single ring with 100 stations, one per repeater. System B consists of four 25 stations rings linked by a bridge. If the probability of a link failure is Pl, a repeater failure is Pr , and a bridge failure is Pb , derive an expression for parts (a) to (e). 50 points

a. Probability of failure of system A.

b. Probability of complete failure of system B.

c. Probability that a particular station will find the network unavailable, for systems A and B.

d. Probability that any two stations selected at random will be unable to communicate for systems A and B.

e. Compare values of parts (a) and (b) for Pl = Pr = Pb = 10-2