# O.R. Brainteasers

In finance, they have lots of books and sources for interview questions. Especially, 'brainteasers' are pretty famous. A brainteaser can be logical deduction questions or questions like 'when does the hour and minute hands of a wall-clock are exactly at the same place after 3 PM'. There are also questions dedicated to the finance field.

My question is the following: how kind of questions can we ask for OR & Analytics jobs? Of course, it can not be very detailed mathematical questions since the expertise in OR can vary from financial modeling to discrete optimization. Hence, I am thinking about a good way to measure the analytical thinking skills of applicants for the OR & Analytics fields.

Hence, I will be happy to see whether:

1. We have good sources for such questions
2. We can give some good examples here showing what kind of skills does this question measure

Let me list some examples. An OR & Analytics applicant needs to be really good at induction, so without going in much detail we can ask:

Use induction to show that \begin{align*} \sum_{k=1}^n k^3 = \frac{n^2 (n+1)^2}{4}. \end{align*} Hint: For induction you need to define a base case, ....

Or, even to measure mathematical modeling skills we can again stay in the high school level and ask questions like:

George is 1 year more than twice Luke's age. 3 years from now, Maggy will be 27 less than twice George's age. 4 years ago, Maggy was 1 year less than 3 times Luke's age. How old will Maggy be 3 years from now?

Or, with a very simple question, we can measure the knowledge of functions and calculus with:

On what interval(s) is the function $$f(x) = x^3 e^x$$ increasing?

Note: I am aware that there is a similar discussion here, but I think it can be nice to give some problems here as a resource for applicants and application receivers.

• Since your question can have some "opinion-based" responses, I give you my opinion. I'm totally against brainteasers! People function very differently and a brainteaser during an interview doesn't prove anything. Some people can think on the fly and some need more time (some students shine in take-home exams and some in in-class exams). Some people understand a problem when it's described to them and some need to walk around the room or doodle. Also, it's an interview and there will be an additional stress factor involved. So, my opinion: do brainteasers for fun but not for evaluation!
– EhsanK
Nov 9 '19 at 17:03
• A good job interview is about testing how well the candidate will perform in the situations they will experience in the job they are applying for. Doing OR work is about being able to understand and formulate problems, having great technical skills, and communicating well! I have written this answer about how I test for this in job interviews: or.stackexchange.com/a/1056/140 Nov 10 '19 at 15:21
• Are you asking for a list of resources for these types of problems, or a list of the problems themselves? Those feel like two different questions to me. Nov 10 '19 at 17:43
• Completely agree with @EhsanK and MichaelLindahl here, I think brainteasers are counterproductive and will not give you the most qualified candidate for the job. What makes the most sense in my opinion is to ask the candidate to bring along a piece of work that they did and ask them to walk you through it. Then you can question him/her choices and see how he/she approaches a problem. Nov 11 '19 at 8:44
• If I want to know whether a candidate can do calculus and induction, usually I can just check their academic transcripts. As per Michael's comment, the things I'd be more likely to test in an interview situation are the ability to formulate a problem and to communicate/collaborate with others. These are critical skills that can't be easily evaluated from transcripts. Nov 11 '19 at 22:54