Katkat
Back

Calculate Expected Flips for Heads-Tails Sequence

YahooData Scientist · Technical Screen
EasyData ScientistTechnical ScreenStatistics & Math

Last updated

This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Calculate Expected Flips for Heads-Tails Sequence states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

Scenario

Product manager asks a quick probability check during a design review to gauge statistical intuition.

Question

You flip a fair coin repeatedly until the sequence Heads–Tails (HT) appears consecutively. What is the expected number of flips required?

Hints

Model as states: start, last flip H, and absorbing HT; use expected value equations.