MediumProbability

Russian Roulette — Spin?

Jane StreetCitadel

A 6-chamber revolver has 2 bullets in adjacent chambers. The cylinder is spun, the trigger is pulled, and it’s empty. If you do NOT re-spin, what is the probability the next pull is also empty?

Approach

Condition on which empty chamber fired first.

Only the chamber right after a bullet is dangerous.