How Many Manholes Are There In NYC?

By on

“Tell me a little bit about yourself”, and “Why would you be a good fit for this position” are the typical questions a potential employee would be asked during an interview.

 

However, some employers have been asking much more complex questions also known as “guesstimates” and “brainteasers”. These types of questions are commonly asked by Wall Street firms, consulting firms, and tech firms. What the interviewer really wants to know is, “Are you creative? Can you problem-solve? Can you think on your feet?”

 

Here are just a few guesstimates and brainteasers in the interview business, along with how to answer them.

 

  1. How many square feet of pizza are eaten in the United States each month?
    This is a classic guesstimate question where you need to think aloud. And so first you round the U.S. population to 300 million people (it’s actually about 315 million but rounding will be much easier and your interviewer will not score you lower for rounding). Then estimate how many people eat pizza. A decent educated guess is two out of every three people, or 200 million. Now let’s say the average pizza-eating person eats pizza twice a month, and eats two slices at a time. That’s four slices a month. If the average slice of pizza is perhaps six inches at the base and 10 inches long, then the slice is 30 square inches of pizza. So, four pizza slices would be 120 square inches (30 times 4). Since one square foot equals 144 square inches (12 times 12), let’s assume that each person who eats pizza eats one square foot per month. Since there are 200 million pizza-eating Americans, 200 million square feet of pizza are consumed in the U.S. each month. To summarize: 300 million people in America, 200 million eat pizza, average slice of pizza is six inches at the base and 10 inches long or 30 square inches, average American eats four slices of pizza a month, four pieces times 30 square inches equals 120 square inches (one square foot is 144 square inches), so let’s assume one square foot per person, and thus one square foot times 200 million people equals 200 million square feet of pizza a month.

 

  1. If you look at a clock and the time is 3:15, what’s the angle between the hour and the minute hands?
    Usually, if the answer to a brainteaser seems too easy, chances are the answer’s wrong. And in this case, the answer is not zero degrees. The hour hand, remember, moves as well. That is, in addition to the minute hand. And so, at 3:15, the hour hand and the minute hand are not on top of each other. In fact, the hour hand has moved a quarter of the way between the 3 and 4. This means it’s moved a quarter of 30 degrees (360 degrees divided by 12 equals 30). So the answer, to be exact, is seven and a half degrees (30 divided by four).

 

  1. How would you estimate the weight of the Chrysler building?
    This is a process guesstimate where the interviewer wants to know if you know what to ask. First, you would find out the dimensions of the building (height, weight, depth). This will allow you to determine the volume of the building. Does it taper at the top? (Yes.) Then, you need to estimate the composition of the Chrysler building. Is it mostly steel? Concrete? How much would those components weigh per square inch? Remember the extra step: find out whether you’re considering the building totally empty or with office furniture, people, etc. If you’re including the contents, you might have to add 20 percent or so to the building’s weight.

 

  1. If you have seven white socks and nine black socks in a drawer, how many socks do you have to pull out blindly in order to ensure that you have a matching pair?
    The answer is three: if the first one is one color (say, white), and the second one is the other color (black), then the third one, no matter what the color, will make a matching pair. (Sometimes you’re not supposed to think that hard.)

 

 

The first rule of guesstimates and brainteasers is there are two types of wrong answers: the random guess and giving up.

 

The second rule is interviewers, in asking these questions, are trying to gauge your composure, thoughtfulness, and creativity, but not necessarily your ability to get the right answer. In fact, with respect to guesstimates—questions that ask you to come up with a figure, usually the size of a market or the number of objects in an area—interviewers themselves don’t always know the exact answer. Thus, the best approach for a guesstimate question is to think of a funnel: begin by thinking broadly, then slowly narrowing down the situation towards the answer.

 

Happy Tuesday & Happy Selling!

Kevin