What is the expected number of tosses of a fair coin to get HTH?

What is the expected number of tosses of a fair coin to get HTH?

Approach: Use martingale method or set up system of equations for overlapping patterns.

10. For pattern HTH, expected waiting time = 2^3 + 2^1 = 8+2=10.

Follow-up: What about pattern HHT?

Key concepts: pattern matching, overlap, expected waiting time.