240.HHT Before HTT
★★★markov chainsJane Street
A fair coin is flipped repeatedly until either the pattern HHT or the pattern HTT appears. What is the probability that HHT appears first?
Sign in to submit an answer and track it toward your stats.
Sign inHint
Again both patterns open with H. Ask what happens once you reach two heads, and what a T after a single H commits you to.
Want timed drills, mental math, and a market-making game too? Try the full practice suite →