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Estimate the number of lakes in the world

Updated: Nov 18, 2022

Mobiprep has created step by step solution to estimation questions for all product management and consulting interview questions to help you with the mastering placement interviews. So let’s get started with the estimation questions.

Our team has curated a list of the most important product management frameworks asked in interviews such as Google, Deloitte, McKinsey, Microsoft, EY, ZS and many more. The frameworks are created from the best practices adopted by previous year candidates.

In this estimation question we have analysed the market size of the number of lakes in the world. Check out the step-by-step answer created by Mobiprep experts.

Estimation Question Step-1: Segmentation


Radius of Earth = 6400 km

= 2^6*100


Surface area of Earth = 4*3.14*2^6*2^6*100*100

= 12.56*4096*10000 sq. km

Assuming, Earth to be a perfect sphere. So, 510 million sq. km (approx)

Now, we also need to ask whether, we want only fresh water lakes or we also take in saline lakes.

Estimation Question Step-2: Solution

Lets assume, we need only fresh water lakes

Segmentation of water on earth

Now, let us take that an average size of a lake is 100*100 sq. m or 100 lakes/sq. km

Therefore, total number of lakes = 14000*100

= 14 lakhs lakes

(According to Google estimates, we have approx 20 lakhs lakes. But these can be both fresh water and salt water.)

Also, we can say that these lakes are natural lakes. There may be some artificial lakes made by human beings for their use.

Type of water bodies on earth

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