Summer Internship Interview Questions | Glassdoor

# Summer Internship Interview Questions

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Summer internship interview questions shared by candidates

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### Assistant Trader Summer Internship at Jane Street was asked...

Feb 26, 2010
 Flip a coin until either HHT or HTT appears. Is one more likely to appear first? If so, which one and with what probability?13 AnswersLet A be the event that HTT comes before HHT. P{A} = P{A|H}P{H} + P{A|T}P{T} = .5P{A|H} + .5P{A|T} P{A|T} = P{A} therefore, P{A|H} = P{A|T} P{A|H} = P{A|HH}P{H} + P{A|HT}P{T} = (0)(.5) + P{A|HT}(.5) Therefore, 2P{A|H} = P{A|HT} P{A|HT} = P{A|HTT}P{T} + P{A|HTH}P{H} = (1)(.5) + P{A|H}(.5) 2P{A|H} = .5 + P{A|H}(.5) P{A|H} = 1/3 and P{A|H} = P{A}, therefore, P{A} = 1/3 So, HHT is more likely to appear first and it appears first 2/3 of the time.P{A|H} = P{A|HH}P{H} + P{A|HT}P{T} = (0)(.5) + P{A|HT}(.5) Need help - - why is P{A|HH} = 0 ?P(A|HH) = 0 because after a sequence of consecutive heads, you can no longer achieve HTT. The moment you get a tail, you will have the sequence HHT. This the reason HHT is more likely to occur first than HTT.Show More ResponsesP(A|HH) = 0 because after a sequence of consecutive heads, you can no longer achieve HTT. The moment you get a tail, you will have the sequence HHT. This the reason HHT is more likely to occur first than HTT.HHT is more likely to appear first than HTT. The probability of HHT appearing first is 2/3 and thus the probability of HTT appearing first is 1/3. Indeed, both sequences need H first. Once H appeared, probability of HHT is 1/2 (b/c all you need is one H), and probability of HTT is 1/4 (b/c you need TT). Thus HHT is twice is likely to appear first. So, if the probability that HTT appears first is x, then the probability that HHT appears first is 2x. Since these are disjoint and together exhaust the whole probability space, x+2x=1. Therefore x=1/3.You guys seem to be mixing order being relevant and order being irrelevant. If order is relevant (meaning HHT is not the same as HTH) then this has a 1/8 of occuring in the first 3 tosses. Also HTT has a 1/8 chance of occurring in the first 3 tosses, making them equally likely. Now, if order is not relevant. (so HHT and THH are the same), then this has a (3 choose 2) * (1/8) probability of happening in the first 3 tosses. The same goes for HTT (which would be the same as THT etc and others) so this has a (3 choose 2) * 1/8 probability of happening in the first 3 tosses as well. Either way they come out to being equally likely, please comment on my mistake if I am doing something wrong.Ending up with HHT more likely (with probabilty 2/3).HHT is more likely (2/3) probability. People with wrong answers: Did you not Monte Carlo this? It takes 5 minutes to write a program, and you can then easily see that 2/3 is correct empirically.I don't get it. Shouldn't P{A|HH} = P{A} in the same sense that P{A|HTH} = P{A} from both HH and HTH we have get the first H from HTT and so it should be P{A|HH} = P{A|HTH} = P{A} Am i wrong?sorry, i meant: I don't get it. Shouldn't P{A|HH} = P{A|H} in the same sense that P{A|HTH} = P{A|H} from both HH and HTH we have get the first H from HTT and so it should be P{A|HH} = P{A|HTH} = P{A|H} Am i wrong?Above link is the best solution I have seen for this problem http://dicedcoins.wordpress.com/2012/07/19/flip-hhh-before-htt/Apologies, Below*Here's my answer. Let x = probability of winning after no heads (or a tail). y=probability after just one heads. z=probability after two heads. w=probability after HT. Thus x=(1/2)x+(1/2)y, y=(1/2)z+(1/2)w, z=1/2 + (1/2)z, w=(1/2)y. Therefore, z=1, y=2/3, w=1/3, x=2/3. We wanted x at the beginning, so it is 2/3 that HHT comes up first.

### Assistant Trader Summer Internship at Jane Street was asked...

Feb 26, 2010
 How many digits are there in 2^50?5 Answerslog2(2^50) / log2(10) = 50 / 3.3 ~= 152^50 / 10 = 16 * 2^46 *1.616 digits: 2^50 = (2^10)^5 = 1024^5Show More Responsesevery 3 powers of 2 the number of digits increases by 1. 50/3 = 16.67, so there are 16 digits.With these brain teasers, is it allowed to use scratch paper? Is there a favored approach between trying to work quickly and mentally as opposed to thoroughly and methodically? I can see the pro's and con's of both, and I'm just curious whether I should practice one way or another.

### Summer Internship - Quantitative Investment Strategies at Goldman Sachs was asked...

Apr 10, 2012
 Suppose that you have a fair coin. You start with \$0. You win 1\$ each time you get a head and loose \$1 each time you get tails. Calculate the probability of getting \$2 without getting below \$0 at any time.5 AnswersDraw a tree to have an idea of how to compute the probability. The flips are all independent with each other.1/31/3 Because if he requires 2 heads = \$2, then it means he require HH out of {HH,HT ,TH,TT} We cannot consider TT because it would turn to zero. Therefore, he has 1 chance out of 3. Hence 1/3.Show More ResponsesEach flip has a .5 possibility of being head. (.5)(.5)=.25 or 1/4Marchov chain with 2 and -1 absorbing OR geometric series 1/4^n from 1 to inf=1/3

### Summer Software Engineering Internship at Symantec was asked...

Feb 9, 2012
 What is the difference between a Class in C and an Object in C++?2 AnswersC has no class- C is a functional programming language!!!!!I think you mean difference between class and object in C++, C is a low level language with no Class functionality (it does have struct however). A class is a collection of variables and functions for the purposes of OO programming. An object is an in stance of the class that can call its member functions and variables

### Summer Software Engineering Internship at Symantec was asked...

Feb 9, 2012
 What is the difference between a signed and unsigned integer variable type?2 AnswersSigned can hold positive and negative numbers, unsigned numbers can only hold positive numbers (or 0)signed value ranges from (-Max_Val, Max_Val), while signed goes from (0, 2*Max_Val). Max_Val is the predefined maximum value for the specific data type. They both have the same range of 2*Max_Val

### Summer General Internship at Discovery, Inc. was asked...

Mar 24, 2014
 The Survey was really easy...2 AnswersListed all my skillsHey! I haven't heard anything back yet either (idk if you have by now though). I know someone who works at Discovery and I had her ask about it and she was told everyone should hear back by the end of April (which is very confusing since the e-mail for the video audition said we should hear by March 31st). Have you heard anything by now?

### Assistant Trader Summer Internship at Jane Street was asked...

Feb 17, 2014
 A survey is given to all passengers on a number of different planes. The survey asks each person how full their plane was. The people answer honestly. If 50% of people claim that their plane was 80% full, while the other 50% claim that their plane was 20% full, how full was the average plane?2 Answers32%, I think? I totally blanked during the interview and it took me a while to get.Let's say each plane holds 100 people. If someone is on a plane which is 80% full, then each of the 80 passengers will say the same thing. Similarly, if someone is on a plane which is 20% full, then each of the 20 passengers say the same thing. We want the number of people who say 80% to be equal to the number of people who say 20%, so for each plane which says 80% there must be four which say 20%. The average is therefore (1/5)80% + (4/5)20% = 32%.

### Software Development Engineer In Test/SD Summer Internship at Microsoft was asked...

May 17, 2012
 Given an array of positive and negative numbers, give an algorithm that would find the sequence of numbers that give the largest sum. The numbers have to be in sequential order. 2 AnswersThe naive algorithm will take O(n^2) time, but it is very easy to code. The divide and conquer algorithm will take O(nlgn) time, but a little challenge to implement.If by "sequential order" you mean that the indices of the numbers in the subsequence must be consecutive, I think this should work in O(n): int main() { int best[N], B, i, a[N]; //input to a; best = a; B = a; for(i = 1; i best[i-1]) best[i] = B + a[i]; else best[i] = best[i-1]; B = max(a[i], B + a[i]); } return best[N-1]; return 0; }

### Project Management Summer Internship at Rolls-Royce was asked...

Mar 8, 2014
 For the on campus interview it was: "What global trends influence our business most?"1 AnswerAnswer they were looking for was fuel prices and availability/prides of rare earth metals.

### Operational Summer Internship( Either FX Or EQ) at Jefferies was asked...

May 15, 2013
 Tell me a project you do at your college1 Answerreally complex to elaborate! you'd better be well prepared in short with simplicity.
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