Tuesday 20 December 2016

Interview Question : Finding Number Of Cars in City

Finding Total Number Of Cars ..... interview

Interview was going on .... then one interviewer asked :

One Interviewer Asked: Assume that the population of Delhi is 2 crores (20 million)

How many number of car are there in Delhi City?


( Candidate) she get it quickly that this is a type of guesstimate. 

There is no correct/incorrect answer in this case and the interviewer usually wants to see thought process in such question.

Candidate Replied : 

As the population of Delhi is 2 crores (20 million)

Let the average family size in Delhi be 4 So the number of households can be estimated to be 50 lakhs (20/4 million)

Now, let us assume that only 50 - 60% of the population can afford a car.

 For simplicity, assume that 50% of the families owns one or more cars.
So 25 lakh households own 1 or more cars

Let us assume that of these, 75% own only 1 car , 20% own 2 cars and 5% own 3 cars (assuming no household has more than 3 cars)

So households with 1 car = 18.75 lakh(1.875 million) 2 car = 5 lakh (500,000) 3 car = 1.25 lakh ( 125,000)

So total number of cars in delhi can be estimated as 18.75 + 5*2 + 1.25*3 = 32.5 lakh which can be rounded off to 32 lakh (3.2 million)

So we can estimate that the number of cars in Delhi to be 32 lakh (3.2 million).


Interviewer gave her good scores for her thought process

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