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Guesstimates

  • July 30, 2025
  • Guesstimates

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Disclaimer: This material has been curated by the GoCrackIt team and is an indicative list and not an exhaustive list. 

Q1. How many iPhones users are there in India at present?

Ans. Suppose, we are considering all models of the iPhone.

  • There are 1.39 billion Indians. Out of which, 40% of the population includes children and senior citizens. This means that children and senior citizens will be excluded which leaves us with 834 million people that can own an iPhone.
  • Now, out of all these people, we will consider the upper class and upper-middle class who can own an iPhone. For this, we will exclude the lower middle class, which is around 14%.
  • This brings the probable number to 717 million. As per the statistics, the market share of the iPhone is 3.2%. This means there can be 22 million possible iPhone users in India.

Q2. How many refrigerators are sold in India every year?

Ans. First of all, clarify whether we will consider domestically produced refrigerators or both domestically and internationally manufactured refrigerators.

  • Suppose we are considering both, then we will exclude segments based on a few factors.
  • Consider the population of India and now, divide it by the average number of members in Indian Households i.e. 4 members per household.
  • Now, further segment the population into urban (tier 1), suburban (tier 2) and rural (tier 3).
  • Classify these tiers as per availability of electricity (1.3 million Indians do not have access to electricity).
  • Exclude the number of people below the poverty line.
  • Your approximation should also include the annual demand for new refrigerators and replacements.
  • Consider the average life of a refrigerator (10 years) and the annual projected growth rate of refrigerators in your calculation.

Q3. What is the average number of laptops sold in Mumbai every day?

Ans. Here, we will consider both the demand and supply of laptops. I assume that supply is more than demand since the location is Mumbai.

  • The ‘18-45’ age group will be the target market for the suppliers which is around 70% of the population of Mumbai.
  • The average cost of a laptop is around 40,000 rupees and assuming that any person who earns more than this amount can buy a laptop.
  • This comprises about 70% of the population of Mumbai.
  • Assuming that 70% of this population already owns a laptop and only 30% might purchase a new one.
  • Let us now assume that the demand for personal computers will increase by 20% whereas the demand for buying laptops will increase by 80%.
  • So, the average number of laptops= total of the above-mentioned metrics divided by the number of days in a year.

Q4. What number of tennis balls can fit inside a room?

Ans. First of all, you need to know the size of the tennis ball. You can do one of the two things: ask the interviewer or assume its size.

  • Now, calculate the volume of the room and divide this volume by the volume of tennis balls. You need to consider that the balls are round and a regular arrangement will leave empty space due to their shape.
  • Suppose, the room has only 4 seats. The room may fit 5 chairs in the vertical direction and 10 chairs in the horizontal direction. It seems as if this arrangement can be repeated 10 times to fill the room. This means that the room can roughly fill 500 seats.
  • The total space occupied by the seat should be considered here (sp). Here sp= (4 x 2 x 1)ft = 8 ft. This means that the room’s volume is approximately sp x number of seats = 8 x 500 = 4000 cubic ft.
  • The tennis ball seems to occupy 4 cubic inches of area, the number of balls = volume of room/ area occupied by balls = 1000 balls.
  • Since tennis balls can be packed up to 70%, hence the total number of balls is 700.

Q. How many cups of tea were consumed in Delhi in a month?

Ans. We will assume that fewer people will consume tea during the weekend since these are not working days. The next number to consider is the population.

There are 20 million people in the city and let us assume that 20% of youngsters do not consume tea. Out of the rest, 30% consume tea on a daily basis, 20% consume tea occasionally and 10% do not consume tea. Let us say that daily drinkers could be having three cups of tea in a day and occasional drinkers consume tea twice a week.

Then, the total number of cups of tea consumed will be:

  • Daily drinkers – 3 x 0.2 x 7 = 4.2
  • Occasional drinkers – 1 x 0.2 x 1 = 0.2
  • Non-drinkers= 0
  • Total= Daily + Occasionally + Non-drinkers = 4.4 cups in a day
  • Per month = 4 x 4.4 x 1.4 crore = 24.64 crore cups.

How much paint will be required for painting a 20 m x 20 m wall?

Ans. Let us estimate the amount of paint required for every square meter. Now, we will find the area to be painted.

  • The wall to be painted will have the main area as 20 m x 20 m which is 400 square meters.
  • Let us assume that the depth is 1 mm.
  • We will also consider that the oil in half of the paint has dried after a few hours of the paint application on the wall.
  • Let us consider the width of the paint to be considered as 2 mm.
  • Thus, the volume to be painted is 400 square meters x 0.002 meters = 0.8 meters cube of paint is required.

Q. Estimate the number of televisions sold in india every month. Show your assumptions & calculations in your answer along with the final number.

Ans. Let us start with the population of India since this is an official figure we know. Currently, there are 1.40 billion people in India. 

  • Approximately 66% of the households own television in India.
  • Most households have an average of 1.2 televisions.
  • As an estimate, 231 million television sets are bought each year in India.
  • On an everage, most televisions, be it an OLED, LED or LCD have an average lifespan of 10 years.
  • Industry average for television replacement rate is 10%
  • As an average, number of new households that are build every year is 0.5% of the total population

Now, let us come to the calculation part:

  • Number of households owning television will be 0.92 billion.
  • Number of televisions in each home 1.10 billion
  • Average lifespan of a television is 10 years
  • Approximate number of televisions that are replaced every year 1.10 billion x 10% = 110 million televions
  • Average number of televisions replaced every month = 110 million/12 = 9.16 milliom  television
  • Number of new household formed every year = 1.40 billion x 0.5% = 7 million households
  • New television for the new households = 8.4 million households

Final estimate: 9.16 million + 8.4 million = 17.56 million televisions

Source: For all above
https://www.shiksha.com/online-courses/articles/top-interview-guesstimate-questions-and-answers/

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