55. Independent flips of a coin that lands on heads with probability p are made. What is the probability that the first four outcomes are

(a) H, H, H, H;

(b) T, H, H, H?

(c) What is the probability that the pattern T, H, H, H occurs before the pattern H, H, H, H? HINT FOR PART (C): How can the pattern H, H, H, H occur first?