Rolling until a high face, at a cost
You roll a fair six-sided die repeatedly and stop the moment it shows a 5 or a 6. Each roll costs you $2. What is the expected total cost of playing until you stop (in dollars, to two decimals)?
Show hints (2)+
- First get p from 'a 5 or a 6' (two faces of six), then E[rolls] = 1/p.
- Multiply the expected number of rolls by the $2 per-roll cost.
Answer
Reveal answer →Final answer
6
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Asked at: Timed Mental-Math & Sequences, Game-Based Aptitude