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Interview questions

  1. Feb 16, 2012 #1
    These came up for a job interview and they had to be answered relatively quickly (most of them should be answered within one minute):

    How many could you answer and how quickly?
  2. jcsd
  3. Feb 16, 2012 #2
    Wow. What kind of job was it?
  4. Feb 16, 2012 #3


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    What kind of job was this for? How do you have a copy of the test? When I've taken employment tests, you were not allowed to take anything with you so that it can't be given out.
  5. Feb 16, 2012 #4
    I just picked a few low hanging fruit.
    2) 3.5 because the rule that makes you stop playing has no effect on the expected value.

    7) While there are input letters take an input letter and see if it is a space. If it is not a space, put it into a LIFO queue. If it is a space, then take the letters off of the LIFO queue one at a time and print them, then print the space. When there are no more letters, take the letters off of the LIFO queue one at a time and print them. Stop.

    10) Spin the barrel again for a 2/3 chance of surviving. If you pull the trigger without spinning you will have a 1/2 chance of surviving.

    11) 1400 is cheaper because you subtract the strike price from the sale price to determine the value.

    12) This one is weird. Options sell in a market that is independent of their underlying securities. However, in general, there is some correlation to: The underlying security, the strike price and the expiration date.
  6. Feb 16, 2012 #5


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    The OP is a student, I'd be careful about giving answers.
  7. Feb 16, 2012 #6
    FIG @ GS, memory
    Didn't ask for solutions, just wanted to discuss the aspects of getting jobs at these types of firms.

    Here's some others asked at another company:

    How many ridges are on a quarter?
    How many libraries are in the U.S.?
    How many traffic lights are in Manhattan?
    Rank yourself from 1-10, 10 being the best in the following 5 qualities. The total cannot be greater than 35: Intellect, teamwork, communication, finance, attitude
  8. Feb 16, 2012 #7


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    Physicists know this kind of question as "Fermi questions," after Enrico Fermi who liked to spring them on his students. The point is not the actual question or answer, but rather the process that you use to estimate an answer, within an order of magnitude or so.

    A classic Fermi question is "How many piano tuners are there in Chicago?"
  9. Feb 16, 2012 #8


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    I wouldn't work there. I'd rather work somewhere they ask you easy questions - like, "How high can you count on your fingers and toes?" Except I'd need a slide rule to even answer that question.

    Actually, some of these are easy; some I'd at least know how I wanted to start them, but would need to think about them for a few to refine my answer (the robot question, for example), and I wouldn't have a clue about #11 or #12. Plus, I couldn't answer #5, but at least I knew that immediately.
  10. Feb 16, 2012 #9
    FIG? Does that stand for Fortress Investment Group?...
  11. Feb 16, 2012 #10


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    From the math, probability, economis and financial questions and terms, I'd imagine this was a financial services company.
  12. Feb 16, 2012 #11
    Well, I wouldn't qualify, but I like the questions. #5 is interesting, for example. Best I could come up with that with a fair coin you can chose between four things A,B,C, and D. So you flip until you hit either an A, or a B or C. So it has an answer as a limit. Can it be done easier?
  13. Feb 16, 2012 #12


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    With enough coin flips, you could get close to 1/3 and 2/3 by merging several possible results into one category (4 heads & 3 heads out of 4 flips, for example), but it's impossible to get an exact multiple of 3 using only powers of 2.
  14. Feb 16, 2012 #13
    Yeah, I had the same conclusion. The answer has to be a 'limit.'
  15. Feb 16, 2012 #14
    No, just flip twice, 2 heads is A, 1 head, 1 tail is B, 0 heads is ignored.
  16. Feb 16, 2012 #15
    That's the same answer as I gave. (Chose between A,B,C and D with chance 1/4, but try again on D. )
  17. Feb 16, 2012 #16


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    Clearly, you use the coin to buy a 2/3-headed coin.
  18. Feb 16, 2012 #17
    What about #2? Very sloppily I came up with less than 7, but I am very unsure about it.
    Last edited by a moderator: Feb 16, 2012
  19. Feb 16, 2012 #18
    I googled it. One of the questions is supposedly from a Goldman Sachs interview (according to google).
  20. Feb 16, 2012 #19
    Does #9 have a solution?
  21. Feb 17, 2012 #20
    These are typical google/facebook interviews.

    I was successfully able to answer question #6 in one of my interviews.
    while(!markerSet) {

    go left;
    go left;
    go right;
    set marker;
    while(!peerFound) {
    go left;

    for(c=each character in the string) {
    if (c == NULL || c == 'space') {
    while (!stackEmpty)) {
    if (c == NULL) {
    } else {
    push(stack, c);
    Last edited: Feb 17, 2012
  22. Feb 17, 2012 #21
    Yeah, these I found trivial. I didn't bother about them. And I didn't bother about #1 though I don't know the answer by heart.

    I don't believe you got the right answers though. The #6 should be something like 'forall n: do n steps left, retreat, do n steps right, retreat' But the question is underspecified, you need to know that the robots take alternate turns.

    The #7 is easy too. Should be something like: 'split on space, reverse the words, concatenate the result.' You didn't do anything that resembles that.
    Last edited by a moderator: Feb 17, 2012
  23. Feb 17, 2012 #22
    My answer is correct.

    The logic is,
    Move slow (left,left, right) in one direction until you find a marker set. And while moving, set the marker.

    Once you find the marker set (that means, the other robot has visited this spot), move faster (continuous left), so you would eventually meet the other robot that is moving slower (left, left, right).

    I didn't expand the push() and pop(). Look for stack data structures.
  24. Feb 17, 2012 #23
    I could do four of them for sure, and I could take a pretty good stab at about another three of them. Only having a minute each would be trouble, because I don't always think that quickly.
  25. Feb 17, 2012 #24
    Oh, I understood that both robots drop a marker where they are dropped. My answer would work too. Now I look at it more closely, hmm, I guess you can't do something n times, so you're answer is better.

    Hmm, I'll look at it again.
    Last edited by a moderator: Feb 17, 2012
  26. Feb 17, 2012 #25
    The only interesting for me was #9 I think. (But I didn't really bother doing most of them under a minute.)
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