Quantitative Trader Interview Questions | Glassdoor

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Quantitative trader interview questions shared by candidates

## Top Interview Questions

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Jan 2, 2010

Jan 2, 2010
 You flip four coins. At least two are tails. What is the probability that exactly three are tails? Do this in your head, you are not allowed to write anything down for this question.8 Answersprobability you get 3 tails is if you have 1 tail in the remaining 2 coins. This is just one halfits 4/11... it'd only be one half if they told you the first two coins were tails. Use bayes rule or actually write out all the possibilitiesbayes' theorem ftwShow More Responsescan you show me the math behind it? i got P(B|A) x P(A) / P(B) = (1x 1/4) / (5/8)=2/5...There are 16 (i.e., 2^4) possible outcomes. There is one way to get zero tails (i.e., HHHH), one way to get all tails (i.e., TTTT), and four ways to get only one tail (i.e., THHH, HTHH, HHTH, and HHHT). All other 10 (=16-6) outcomes have three tails, hence P=10/16.At least two are tails, no HHHH neither THHH, HTHH, HHTH, HHHT. 2^4-5=11 possible scenarios. Three tails, HTTT, THTT, TTHT, TTTH = 4 cases P=4/11The easy way to work this problem out is that knowing the sample space contains 2 coins (4 choose 2 = 6 ways), 3 coins (4 choose 3 = 4 ways) or 4 coins (4 choose 4 = 1 way). Hence, the probability that there are 2 tails provided the fact is 4 / (6 + 4 + 1) = 4/11.Three tails: 4 At least two tails: 6 (2 tails), 4 (3 tails), 1 (4 tails) 4/11

Apr 13, 2010
 How many 0s in 100! ?5 AnswersThis seems to be a common one in finance interviews. Just count the number of 5's: it's 20 plus an extra one for each multiple of 25 (25, 50, 75, 100). Total is 24.The question is equivalent to asking how many fives we have from 1-100. Notice that some of the numbers contains more than one 5s. 2+2+3+2+3+2+2+3+2+3=24Since factor 2 is always more, it depends how many 5s in 100! - which is [100/5] + [100/25] + [100/125] + ... = 24, [] means integer part.Show More Responsesall answers are for number of 0's in ending digits.....There're 30 zeros, counted in Python, guys.100! = 93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000

Nov 25, 2013
 If I give you the opportunity to play a game at the end of which the loser pays the winner \$10, and then partway through the game I ask that we each double our bets to \$20 or that you must immediately pay me \$10, what is the minimum probability of winning you must have to keep playing?3 AnswersYou want E(X) \geq -10, where X is the payoff of continuing to play. Therefore, we want P(Winning)(20) + (1 - P(Winning))(-20) \geq -10 which implies P(Winning) \geq 1/4 after cancellation.Just for those who got confused about "\geq" in the most voted answer: "\geq" means ">=", greater than or equal to.thanks for clearing up that confusion

Aug 8, 2016
 Devise a strategy of betting on a seven-game series such that if team 1 wins the series you win \$1000 no matter what and if team 1 loses, you lose \$1000.1 AnswerI hope I understood the question correctly. I assume that I am allowed to place bets on single games with even odds, i.e. I can bet x and then either win or lose x dollars. In this case, I get the following bet amounts depending on the current series result (up to symmetry): 0-0: 312.5 1-0: 312.5 2-0: 250 3-0: 125 1-1: 375 2-1: 375 3-1: 250 2-2: 500 3-2: 500 3-3: 1000 The way to compute the values is by dynamic programming. Let A[i,j] be the profit made if team 1 needs i more wins and team 2 needs j more wins, such that we can complete the game. It is not hard to see for small values like A[1,1] = 0 that there can be only one such value. If we have anything else than 0 dollars when its down to a single game, then there is no valid betting strategy. We have A[0,j] = 1000 for all j, A[i,0] = -1000 for all j, and in general A[i,j] = (A[i-1,j]+A[i,j-1])/2 (we need to be in the middle of the two possible outcomes). The bet amounts are then easy to deduce from the A values.

Jan 22, 2018
 Draw payoff diagram of call and put option and explain. What is the advantage of call option? When do people want to buy a stock instead of option?Be the first to answer this question

Jan 15, 2018
 You have all the clubs from a deck, 13 cards, and you can choose 2 from the deck and get paid their product, where all face cards are considered to be 0. You can pay \$1 to reveal the difference of any two cards you choose, how much would you pay to play this game?1 Answer\$79 = \$90 (maximal win) - \$11 (number of steps to determine where are cards of values 9 and 10 )

Jul 21, 2018
 You have a bag of coins of which one half are real and the other half are fake. You need to pay for 1 1/2 hours of parking at a meter where one quarter gives you 15 minutes. Every time you put in a fake quarter the meter time is reset to 0. How many coins will you have to pull out of the bag ?1 AnswerAssuming all coins in the bag are quarters, also assuming an arbitrarily large amount of coins 15 min == 0.25 hr, need to pay for parking for 1.5 hr --> We know that six coins will have to be pulled odds of each coin being real are 0.5 --> odds of pulling six consecutive real coins are .5*.5*.5*.5*.5*.5 --> (1/2)^6 --> 1/(2^6) --> 1/36 Thus, we can expect that 36 coins will have to be pulled.