If you are planning to interview with any Consulting, IT or Financial firm, you better be prepared for a case question. As ever, it helps if you can see things from the perspective of the interviewer and work out what is behind the question.
The objective of asking a case question is to discover how the candidate thinks, how he or she can handle unexpected pressure and questioning. In most interviews, the candidate will have rehearsed pat answers for the ‘chestnut’ questions, such as “Tell me about yourself,” “How would you describe yourself?” “What are your strengths/weaknesses?” A case question can cut through all this flim-flam and get to the heart of your thought process.

A few years ago, brainteasers were an interview fad, but I believe that these questions tend to entertain the interviewer more than provide insight into the personality and behaviour of the applicant. The truth is, a smart interviewer won’t particularly care if you know how many piano tuners there are in any given city or why manhole covers are round instead of square.

What interviewers will care about is how you approach, analyse and dismantle the problem. The interviewer is looking for creativity, self-possession, your ability to stay focused, to break the problem down, to ask the apposite questions, and to conclude with an approach, a solution or a recommendation consistent with the germane points of the case presented.

Joel Spolsky referenced this very well in his Guerrilla Guide to Interviewing:

Ask the candidate to design something. Jabe Blumenthal, the original designer of Excel, liked to ask candidates to design a house. According to Jabe, he’s had candidates who would go up to the whiteboard and immediately draw a square. A square! These were immediate “No Hires.”

“I’m gonna phone a friend. … Jonathan – why are manhole covers round?”

The good news is that having been through at least one year of business school, you are probably familiar with several case studies, and you have been questioned by your lecturers and classmates numerous times. You may have done the same in an IT-focused degree programme. The bad news is that your textbooks contain pages of data and stories, while the case question is usually just one sentence, so your questioning approach is central to your success (this is why case questions are particularly common for Analyst interviews).

When you are asked a case question, the first thing you should do is take out a pen and write down the question. This helps you to frame your probes for the interviewer and you can always visually reinforce the primary question that needs to be addressed. Next, do not jump right in with your questions. Take a minute to compose yourself. Structure your line of questioning on your pad of paper. Think of what data you need to have elaborated upon in order to make an appropriate recommendation. Think logically. Explain your assumptions. Articulate your point clearly. Demonstrate confidence.

Sample questions:

  • Why are manhole covers round?
  • What is the sum of the numbers from one to 50?
  • The famous physics exam question: Given a barometer, determine the height of a clock tower.
  • How many piano tuners are there in Chicago?
  • You and your neighbour, who aren’t necessarily friends, are planning garage sales for the same day. You are both planning to sell the same type of used appliance in the same condition. You plan to price the appliance at €100. Your neighbour plans to sell his for €40. What do you do?
  • How long would it take to move Mount Fuji?