3.5.4 A coin is tossed repeatedly until three heads in a row appear. Let Xn record the current number of successive heads that have appeared. That is, Xn D 0 if the nth toss resulted in tails; Xn D 1 if the nth toss was heads and the .n????1/st toss was tails; and so on. Model Xn as a success runs Markov chain by specifying the probabilities pi and qi.