Ivy Oct 04, 2018 No Comments
“Estimate the number of cars in Delhi.” That’s a common guesstimate question asked in data analytics and management interviews.
The same question can be asked with slight variations, such as “Estimate the number of cars in your city.” Solving both requires the same logic.
In this post, we will discuss how to approach this kind of question easily and suggest some expert tips for solving guesstimates in an interview.
But let’s first understand…
Guesstimate questions can be the deciding factor for your selection in an interview. So, you have to be careful about them and understand the purpose behind these questions.
So, here’s what the interviewers evaluate when you solve a guesstimate:
We at Ivy Pro School help students learn how to solve guesstimates in our business analytics course. This course teaches students in-demand tools, such as Python, SQL, and Tableau, as well as useful skills like machine learning, database management, etc. If you want to be an expert data analyst and master solving guesstimate, you can join our course.
The key to solving guesstimate questions is making the right assumptions and applying proper logic.
Remember, your approach matters more than the answer. An accurate answer is good, but it’s the way you approach the problem that truly impresses interviewers.
So, here are the 4 steps to solve this problem:
If you don’t understand the guesstimate interview question, ask for clarification. It’s better to confirm what the interviewer is looking for than to head in the wrong direction.
Since you have to find how many cars are in Delhi, so you have to be sure about these things:
Let’s say the exact question is this: How many total personal cars exist in Delhi?
Complex problems are less scary when broken down into smaller, manageable parts. So, divide the question into parts based on factors that influence the answer.
In this case, we can break down the question into 3 parts:
Let’s solve each of those problems one by one:
We can assume the population of Delhi is 3 crores.
Next, in India, a family has, on average, 4 members. So, we can divide the total population of Delhi by 4 to get the total number of families in Delhi.
Next, not all families in Delhi own cars. Most of them can’t afford cars. So we would assume 60% of families don’t own cars and 40% of families own cars.
Now, out of 40%, some families would own one car. And there will be some rich families (a very small percentage) who would own 2 cars.
Let’s say 35% of families own one car, and 5% of families own two cars.
Time to combine all the pieces of the puzzle and do some quick calculations:
The population of Delhi= 3,00,00,000
The total number of families in Delhi= (population)/(number of people in a family) =3,00,00,000/4 = 75,00,000 families
Now, out of these 75 lakh families, we have assumed that 35% own one car and 5% own 2 cars.
So, total number of personal cars= (75 lakhs)x(0.35)x(1) + (75 lakhs)x(0.05)x(2) = 33.75 lakh cars
So, our guesstimate says Delhi has approximately 33,75,000 personal cars.
You can use the same logic to solve questions like, “estimate the number of cars in a city.”
Here are similar questions you can practice to sharpen your mind:
Do the following things to get better at solving guesstimates.
You won’t suddenly get a superpower to solve guesstimates on the interview day. You have to develop that ability by practicing questions every day.
You can look for guesstimates everywhere you go. For instance, when you order a book from Amazon, you can estimate how many people get Amazon delivery in one day in your city.
If you are comfortable with numbers, you can solve guesstimates quickly. So, practice quantitative aptitude questions and try to do mental calculations.
It’s always a good idea to know basic stats like the population of India, the ratio of males to females, the population of a few major cities, etc. This way, you will be able to make good assumptions and impress the interviewer.
Guesstimate questions aren’t about having an exact answer. Instead, interviewers want to see your approach to solving the problem.
So, try to follow a logical approach using reasonable assumptions.
This ability to break down problems, estimate smartly, and communicate your approach confidently is far more important than the accuracy of your final answer.
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