Hey guys I'm having a hard time on this problem ... any help would be great!

In the game of "odd one out" three people each toss a fair coin to see if one of their coins shows a different face from the other two.

a) After one play, what is the probability of some person being the "odd one out"?

b Suppose play continues until there is an "odd one out". What is the probability that the duration is r plays?

c) What is the expected duration of play?