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GUEST COMMENT: If you think those other interview questions were tough…

Back in the day, JPM derivatives desk was known as being the most aggressive of the bulge banks(it still had the legacy team of Bill Winters tenure at the time). Certainly, for challenging interviews it blew all the other banks I looked at (GS, Deutsche, Merrill, Morgan) out of the water.

This was the main reason I accepted JPM in the end: I
knew the guys on the desk thought in really interesting ways.

Apart from the usual ‘how many table tennis balls can you fit in the
London Underground network? How many Jelly Babies can you fit in a
jumbo jet? How many sheets of A4 paper can you fit in this room? How
many golf balls are there in mid flight at any given second of the
day? If I have a dice, and pay 1 for a 1, 2 for a 2… how much
would you pay to role the dice?’ there were a couple of corkers at
JPM, the most memorable one of which was my final question, detailed

HR knocked on the door to remind the interviewer that the time slot was finished, so he said:

INTERVIEWER: “OK, one final question before you go – there is a deck
of cards in a pitch black room. Of the pack, 42 are face down, whilst 10 are face-up. How do you sort the cards into two separate piles, so that in each pile there are exactly 5 face-up?”

ME: “I would shuffle the cards again and again and again, so that any
bias in the original pack set-up was removed, and the positioning of
the cards should revert to unbiased probability. I would then split
the 52 cards into two equal packs of 26, so that the odds revert to
probability, giving the best chance of 5 up in each pack.”

INTERVIEWER: “This isn’t a probability question”

ME: “OK, well if it isn’t a probability question, it is a logical
thinking question. The cards must feel different on each side so they can be identified by touch, or I must be able to switch the light on, or my eyes will slowly adjust to the darkness so I can see at least a bit, or even I can take the cards out of the room and split them outside in the light”

INTERVIEWER: “Stop being a smart a**e. The cards are identical, you
can’t turn the light on, the door is locked, and it is absolutely
pitch black. You can’t see anything now, nor will you ever be able

ME: “OK, I’m going to repeat the question back to you as I heard it,
just to clarify I haven’t missed or misinterpreted any detail” [WHICH

INTERVIEWER: “You’ve got the question exactly right, it’s just the
answer you got wrong”

ME: “Well in that case, I think you’ve given me an unanswerable trick question”

ROOM}: “It’s not a trick question. So I’ll leave you to figure out
why you’ve got it wrong on your train journey home. Thanks for

I left, completely perplexed, and got the train back to uni, thinking
about it the whole way, and thinking that I’d somehow blown my interview on this one final question. The next day I got a call from
HR, offering me the job. When I turned up to work there a few months
later, I asked the guy who had interviewed me what the answer was.

His answer: “Oh, there isn’t an answer. I just thought it would be
fun to mess with your head. You’d got all the other questions right
which I threw at you, and I couldn’t have you going back to uni
thinking you were smarter than JPM now, could I?!”

Who says banks aren’t evil!

Comments (16)

  1. Sorry this article is so utterly boring I fell asleep half way through

  2. @ richardhedge

    Then you missed the best bit

  3. was there a best bit?

  4. Seriously the point of this story is what? I did actually read the whole thing which I then regretted. Looks to me as if you were once interviewed by a padantic pratt on an ego trip, you were then were stupid enough to then go and work for.

  5. Pfff, you should try interviewing for McKinsey, anything else is just child-play..

  6. So, the toughest questions in then world are the “unanswerable” ones? No sh*t, Sherlock.

    The toughest questions I’ve ever asked:

    We are standing on the equator. A gun 1,000 miles directly above fires a projectile that travels at 100 miles a second. Assuming that the earth rotates on its own axis at 1,000 miles an hour, how far away from us will the projectile strike?

    PS. JPM equity derivs desk had nothing on us.

  7. if you find the article so boring or can’t see a point to it, why comment? perhaps you should just stop reading and go to another website. I, at least, cannot see a point to your comment…

  8. @richardhedge2 – that’s “pedantic” not “padantic” and its prat with one t not 2.

    obviously I am not a pedant.

  9. True story. My brother was interviewing for M&A position, 1 hour panel type affair, a senior looking guy sat on the far side whole time and didn’t ask any questions until the end when he said “Tell me a joke”.
    Anyway, bro eventually got the position and met senior guy in corridor a few month later when he was back in London and asked about the joke thing. Said senior said “I hate interviewing but this way I at least get to hear a few new jokes”

  10. fantastic!

  11. Very good article and interesting to hear what problem solving questions are being asked in interviews. Helps us to better prep our candidates for interview. The dimwits who are finding it boring shouldn’t neg everyone else out, go and log onto http://www.thisisjuststupid.com

  12. I can’t see the point as there IS an answer !!!

  13. There is no way unless the facing up stack is kept separate or there is a touch sensitive pattern…

    I’d say I’d metamorphose into david blaine or gain his powers and even make the sorted decks appear outta your butt! Or purchase night vision goggles!

  14. Seriously dude! Given that you couldn’t answer this, and can’t answer this even today, looks like you’re trying to prove exactly opposite to your hypothesis mentioned in your first sentence!

    You can feel (by touching) which pack has less cards – that’s the face-up pack! Take 5 from there and put on the other pack! You’ve achieved what you wanted. Why is it so difficult?!

    Joining McKinsey from IB Reply
  15. ..Had a almost similar question on a phone interview when interviewing at JPM for a internship in commodities trading: “There is a deck of cards in a pitch black room. Of the pack, 42 are face down, whilst 10 are face-up. How do you sort the cards so that in each pile there are exactly the same number of face-up?” ANSWER: If you take the first card from the deck and flip it over. If it was a face down, then you still have 10 face-up in pile 1 and you have 1 face up in pile 2. If it was a face up, then you have now 9 face-up in pile 1 and 0 face-up in pile 2. And if you repeat it 10 times, you end up having the same number of face-up in both piles. So I guess the guy who interviewed you just f*cked up his question…

  16. @ Joining McKinsey from IB – are you a complete moron? The question clearly said “there is A deck of cards in a pitch black room”. “A” meaning a singular deck of cards. Best of luck joining McKinsey if you can’t even read a simple sentence – I would suggest the simple coloring in of pitch books in IB may suit you a lot better!

    Question proves a good point actually – everyone thinks bank interviews are really formal, mathematical etc, when in fact judging from my experiences (and this Q&A backs it up) it’s really to do with good banter/rapport and just being memorable in a good way to the interviewer

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