Jane Street

www.janestreet.com
www.janestreet.com

# Jane Street Interview Questions

Updated Dec 14, 2014
Updated Dec 14, 2014
480 Interview Reviews

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## Candidate Interview Reviews

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1.

Application Details

I applied online. The process took 3 weeksinterviewed at Jane Street.

Interview Details

Made to the second round (45 min phone interview), the first round is doing probability relate questions online. The second round is also problem solving, but is much harder.

Interview Questions
• On a multiple-choice exam with three possible answers for each of the five questions, what is the probability that a student would get four or more correct answer just by guessing?   View Answer
No Offer
2.

## Quantitative Researcher Interview

Interview Details

Submitted resume online and get a phone interview two weeks later

Interview Questions
No Offer
3. 1 person found this helpful

Application Details

I applied online – interviewed at Jane Street.

Interview Details

30 minute phone interview. The interviewer asked approx. 9 math questions ( 3 mental math, 3 probability and 3 word problems). I was given approx. 30 seconds per question. Answered at least 7 of them correctly.

Interview Questions
• What is the probability of getting a sum of 10 if you roll three dice?   View Answers (4)
No Offer
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5.

Application Details

I applied online. The process took 2 weeksinterviewed at Jane Street.

Interview Details

telephone interviews just brain teasers. Missed a trick on the first interview but they still wanted to schedule a second one so it's mostly about the reasoning.

Interview Questions
• person A has a 30 sided and person B has a 20 sided die. both players role and the person with the highest role win (on a draw B wins). the loser pays the winner the value of the winners die.
1. calculate expected value of this game for player A (easy)
2. how does this value change if player B can re-roll and when should he re-roll.
3. now how much is it worth for player A to get a re-roll option in this scenario.
4. remove player A reroll. how many re-rolls do player B need in order for him to be a favorite in the game.

i believed i solved 4 and 2 I had a decent idea but 3 is very difficult since optimal strategy might change based on opposing players optimal strategy.

No Offer
Difficult Interview
6.

Application Details

I applied through college or university. The process took 2 weeksinterviewed at Jane Street in April 2014.

Interview Details

Applied in early April, had first interview a week ago, and second interview yesterday. The interviewer for first round was really nice. Gave me some quick mental math (1,000,000 - 111, 12% of 56, etc), and he then gave me a couple probability questions. Second interview was more difficult - one warm up and then one tough question. Prepare to get wrecked.

Interview Questions
• Expected value of heads and tails of two coin flips -> E(t(10-t) = 10E(t) - E(t^2) = 50 - (25 + 10/4) = 22.5

What is the set of numbers between 2 and 30, without the same common factor (e.g. 26 and 24 share 2, so they cannot be in the same set) that will you give you a max sum?

Using the same rules, what is the highest possible number you can have in a set of 1000?

No Offer
Positive Experience
Difficult Interview
7.

## Staff Accountant Interview

Application Details

I applied through a recruiter. The process took 2 weeksinterviewed at Jane Street in April 2014.

Interview Details

Contacted by recruiter, was sent a series of excel tests. Phone screening, followed by face to face. Face to face involved tests and multiple interviews with personnel. Plan on being there all day if you do well on the tests.

Interview Questions
• "Describe a time when someone you worked with betrayed your trust"   Answer Question
No Offer
Positive Experience
Difficult Interview
8.

## Quantitative Researcher Interview

Application Details

I applied online – interviewed at Jane Street in April 2014.

Interview Details

I applied through website, and got phone interview. The interview consisted of probability and math questions. One is on conditional probability, one is kind of estimation on fraction, and another is probability of a robot question.

Interview Questions
• some probability with a robot, and predict the variance of the number of robot under different circumstances   Answer Question
No Offer
Positive Experience
Average Interview
9.

## Intern Interview

Interview Details

Applied online and heard back within about a week. Good communication; had to demonstrate excellent knowledge of excel and mathematical skills. I did not receive an offer in the end but would be happy to apply again. Have heard great things.

Interview Questions
No Offer
10.

Interview Details

Pre-Interview(10min), Interview(30min)

Interview Questions
No Offer
11.

Interview Details

They were pretty slow in their follow up after interviews, I had to email them every time before they'd remember to send me to the next round. The interviews were interesting and technical. Be prepared to answer questions quickly, without pen and paper, in the first round at least. Later on the questions get harder but they allow you to use writing materials.

Interview Questions
• I did initially misunderstand this question and had to be helped along, but it is fairly difficult to do on the fly anyway: "We're playing a game with an unbiased 30-sided die. Before we roll, we both pick (distinct) numbers between 1 and 30, and then we roll the die. If the number that appears is closer to the number I picked, you pay me, in dollars, the number on the die; if it is closer to the number you picked, I pay you, in dollars, the number on the die; if it is equidistant we do nothing. What's the optimal strategy - do you go first or second, and how do you pick your number? What's your expectation?"   View Answers (3)
No Offer

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