"Guesstimate" case interviews
Guesstimate questions are among the most unnerving questions you may ever have to answer in an interview situation. They can be so "off the wall" as to shake up an otherwise calm, collected candidate.
The approach to guesstimates is basically the same as business cases - you will showcase your ability to analyze a situation and form conclusions about this situation by thinking out loud. The difference here is that you will not necessarily be using a series of questions to gather feedback from the interviewer. Instead, you will drive toward a conclusion through a series of increasingly specific statements. Let's look at an example:How many ping-pong balls fit in a 747?
No, this isn't a joke. This is an actual question used in consulting interviews. If you are a little unsettled by this type of question, it's no wonder. That is exactly the reaction the interviewer is expecting. Remember that the main objective of these questions is to evaluate your poise and professionalism when facing an outlandish situation. How you react to this question when presented will speak volumes about your ability to be professional when faced with a similar business situation at a client.
So, how do you approach a guesstimate question? First, do NOT panic. If you are visibly shaken when presented with a guesstimate or brainteaser, it will hurt you. It is extremely important that you do not lose your cool.
Do not let yourself struggle verbally. You are free to say something like, "That is an intriguing question. May I have a moment to think it through?" This statement immediately shows the interviewer you are still in control and gives you some breathing time to think about a method for answering.
Once you have had a minute to compose your thoughts, be sure and go through your reasoning out loud, so your interviewer can see that you're arriving at your answer in a logical manner. "Don't be anal," suggests one former consultant. "You should realize that for the purposes of a guesstimate, 1,000,553 is the same as a million, and you can divide by 350 if you need to divide by the number of days in the year."
Finally, remember that there is no right answer for guesstimates. It will often not even be necessary to come up with a definitive response like "1,400,350," due to constraints on time. Always work toward a final answer, but do not feel that you have done a poor job if the interviewer moves on to other topics before you are finished. They may simply recognize that you're on the right track and see no reason to keep going.