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The unusual riddle Goldman Sachs might ask you in a quant job interview

If you thought our 101 interview questions asked by Goldman Sachs weren't hard enough... you might be a quant. Quant interviews are typically the hardest of the lot. 

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A Goldman Sachs quant told us that, as part of her interview process at the firm a few years ago, she was asked a series of seven riddles in an hour. This was the least complicated of them:

"In a room there are 253 lions and one steak. The steak is poisoned, so that if a Lion eats the steak, it will fall asleep. While asleep, the other lions will treat it the same as they would treat the steak. If another lion eats the poisoned lion, it too will fall asleep. Each of the lions is intelligent, and aware of the poison and its effects. Do any of the lions eat the steak?"

Think you know the answer? Put it in the comments, and don't cheat by looking at the quant's explanation below! 😑

In a question like this, the process is always more important than the answer, after all there are only two options here, and you could just get lucky. The quant told us that it was all about breaking down the problem into its simplest form. She told us she started with one lion and worked her way up.

One lion would eat the steak, knowing no other lions are around to eat it. If there were two, neither would eat it, because the other lion would eat it along with the steak. If there were three, one would eat the steak, knowing the other two lions wouldn't eat it, for fear of being eaten themselves when they fall asleep. In the case of four lions, none would volunteer, knowing that a group of three would be left behind and that one of them would eat the lion. In a group of five lions, one would eat the steak, because a group of four would remain, and the rationale in that group would be the same as mentioned above.

Continuing this process, a pattern emerged for the quant, in which a lion will eat the steak on an odd number, but avoid it on an even. So, when there are 253 lions, the answer would be yes.

Of course, if you can more effectively argue a reason why it would be no, Goldman Sachs would be all ears. For example, there is a possibility that the lions would all be too risk-averse to participate in a chain that could easily kill them. If you think the answer is the opposite, let us know why.

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AUTHORAlex McMurray Reporter
  • JT
    JTL
    16 September 2024

    No. It states in the present tense that the steak is still in the room.

  • bj
    bjm#55
    11 September 2024

    "Show me the incentives and I'll show you the result". In other words until they explain what motivates the lion its impossible to answer.

    I am not a qaunt, but I am ex-GS employee. My answer: A lion sleeps up to 20 hours a day so would have no hesitancy eating the steak.

  • SR
    SRK
    10 September 2024

    Beyond 2, the number of lions become irrelevant. Assuming, 1st lion will eat the steak following his natural wild instinct; the 2nd lion would eat the sleeping lion, knowing there is no one left to eat him.

    More than 2 lions in this mix, no one will eat it, knowing, there is always another lion who will eat the sleeping lion.

  • Er
    Erika.M
    7 September 2024

    Question is if lions know to behaive.

  • Be
    Bernie B.
    6 September 2024

    While I understand what GT_O1 and maryam2024 are writing, the goal of the riddle is to see if the interviewee can translate a real world problem to maths and work out a solution by induction, which is something the interviewer would expect from a Quant and/or Strategist.

    The prisoner's hat puzzle is similar, alongside some variants, was asked at GS years ago as well as at JPM (https://www.reddit.com/r/puzzles/comments/1clshkv/prisoners_hat_puzzle/).

    See https://en.wikipedia.org/wiki/Induction_puzzles for more.

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