Jane Street Interview Question: 3. There are 30 blue and 30 r... | Glassdoor

Interview Question

Quantitative Analyst Interview New York, NY

3. There are 30 blue and 30 red balls and two urns. You

  play a game. Your opponent has the right to arrange the balls in the two urns as he pleases, without telling you what he did. You then must draw a ball from an urn of your choice. You win $10 if you draw a blue ball, otherwise you get $0. How much would you be willing to pay to play this game?
Answer

Interview Answer

2 Answers

10

Your opponent may put one red ball in a urn, 29 red balls and 30 blue ones in the other. So the probability you get a blue ball is approximately 1/4. So you should be willing to pay $2.5.

Anonymous on Feb 3, 2011
1

I would pay less than 5$ because the expected value of this game is 5$

Anonymous on Feb 2, 2011

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