(Computer project in Matlab) Twenty computers are connected in a network. One computer becomes infected with a virus.
Every day, this virus spreads from any infected computer to any uninfected computer with probability 0.1. Also, every
day, a computer technician takes 5 infected computers at random (or all infected computers, if their number is less
than 5) and removes the virus from them. Estimate:
(a) the expected time it takes to remove the virus from the whole network;
(b) the probability that each computer gets infected at least once?
(c) the expected number of computers that get infected.