Expert advice on tech interviews !

about ferozeh

I was scheduled for two telephone interviews on the same day. After I cleared the first two I was scheduled for a third one.

1st Telephone Interview

My first telephone interview was with an APM who had gone to University of Maryland for school. He was very courteous and engaging in his conversation. After the usual exchange of pleasantries he asked me two questions which were:

• Estimate the number of small businesses in US ?

The most important thing the interviewer sees here is how you think ! Remember to think aloud over the phone.Just tell him what you are thinking and how you intend to go approach the problem. Always start with the easiest solution that comes to your mind and let the interviewer know that you will be adding on the solution. This way while you tell the simplest solution you buy time to think about a better solution in the background.

I gave two answers to the above question. I started with the most basic approach that was tied to the population of the USA. Say, we know that ‘x’ numbers of small businesses are needed to support a population of a million people then we can divide the total population of USA by a million and multiply that by ‘x’ giving a very rough/crude estimate.

I went on to refine the solution i.e. saying that we can further improve the estimate by noting that the population in coastal states would support more small businesses than say in North Dakota. We can then further break it down to city level, much like narrowing the width of rectangles when trying to find the area under a curve by drawing rectanlges of infinitesimaly small width.

This interviewer seemed to buy this answer but this was an average answer as it didn't involve much thought. It didn’t make me stand out in the lot of candidates. Always try to say something in response to such open-ended questions which other candidates are unlikely to say and that would make you look good.

For the improved response try to think what is the first thing that comes to your mind when you hear the word ‘small businesses’, to me it was “economy” and economy brings a lot of economic indicators to my mind. So immediately after finishing the first response, I started out that a better solution would be to use the GDP or some other economic indicator to estimate the number of small businesses.

The trick is simple. Since, big businesses are few and can be counted such as using the Fortune 500 list so take those big businesses and count their contribution to the GDP and subtract that number from the total GDP. Next divide the remainder by the average contribution of a small business to GDP and you’ll have your estimate.

This answer was very well received by my interviewer. He was very happy with me and said he didn’t think of this approach himself. The next question was a puzzle albeit an easy one

• If there are three people in a room and they want to know the average of their salaries without disclosing their individual salaries so how should they go about it?

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