View All num of num See all Photos Jane Street www.janestreet.com Unclaimed Profile Overview Reviews Salaries Interviews Jobs Photos Benefits 22 Reviews 59 Salaries 558 Interviews Follow Add Interview Follow Add Interview Interview Question Researcher Interview Jane Street Two gamblers are playing a coin toss game. Gamer A has (n+1) fair coins, B has n fair coins. What is the probability that A will have more than B if both flip all their coins? Tags: See more , See less 8 Answer Add Tags Answer Interview Answer 2 Answers ▲ 1 ▼ 0.5 Interview Candidate on Dec 7, 2011 ▲ 3 ▼ To see the reason, consider 1 coin from A separately. It is either H or T. If it is H, the A wins if he has at least as many heads as B in the rest of the n coins. If it is T, then B wins if he has at least as many H in the rest of n coins. This is symmetrical and therefore the probability of A winining is 0.5. someone on Dec 21, 2011 Interviews > Researcher > Jane Street Add Answers or Comments To comment on this, Sign In or Sign Up.