Guesstimate questions are important from management interview point of view. These questions are critical for assessing candidate’s take on a problem that lacks complete information.
Guesstimate is the portmanteau of guess and estimate. “How many soaps are sold daily in India?”, “How many cups of coffee are being consumed daily in Delhi?”. These are some of the guesstimate questions. These can only be solved approximately based on the available information.
Table of Contents
- What is Guesstimate?
- Importance of Guesstimate questions
- Interview-Based Guesstimate Questions with Answers
- Tips to answer Guesstimate Interview Questions
What is Guesstimate?
Guesstimate is an approximation based on the available information. Most of the time, only limited information is available. It has more to do with understanding the approach toward the problem. Consider feasible parameters that influence the problem. Interviewers ask such questions to understand if the candidate can come up with a solution to a problem within a set time frame.
Importance of Guesstimate Interview Questions
Guesstimate questions are prepared on the basis of limited details and information. These questions compel the interviewee to use their reasoning and problem-solving ability. Such questions are valuable in several fields where you may have to make decisions based on the availability of few resources. Through these questions, one can gain a different perspective on how a problem can be solved.
Top Interview-Based Guesstimate Questions and Answers
Management students are asked such questions by interviewers to analyze their decision-making and estimation capabilities. Candidates are expected to approximate the answer based on the little information that they are provided with.
Basically, your approach to answering the question is assessed. There is no actual calculation involved. Aspirants who plan to pursue a career as a consultant should also be aware of the concept. You can find below a list of interview-based guesstimate questions with solutions that can be useful to you.
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Q1. What is your strategy for solving a guesstimate question?
Ans. The four-step strategy as given below is quite useful for answering guesstimate interview questions:
Step 1: Clarify unclear terms asked in the question.
Step 2: Break down numbers into small and easy-to-estimate pieces.
Step 3: Estimate each piece mathematically and by using background knowledge.
Step 4: Consolidate every piece to conclude the result.
Q2. What are the different types of Guesstimates based on an approach to solutions?
Ans. Following are the different types of Guesstimates based on the approach to solutions:
- Household Approach: This approach is used for solving household-based guesstimate questions.
- Population Approach: For solving population-related questions guesstimate questions such as finding the number of people consuming something or the number of people living in an area.
- Structural Approach: This approach is used for solving guesstimate questions such as finding the number of aeroplanes landing in a single day.
Q3. Can you provide examples of guesstimate questions?
Ans. Some examples of these questions would be:
- How many packs of Mama Earth face packs are sold each day in India?
- Number of iPhones users in India at present
- The average number of bikes sold in Delhi during the last month
- How many teacups were consumed in Bangalore last week?
Q4. 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.
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Q5. 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.
Q6. 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.
Q7. 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.
Q8. How many balls should you take out of a bag that has red and green balls in order to get two matching balls?
Ans. Suppose that you take out a red ball and then a green ball. After two times, you will automatically get either a red or green ball which means you will own a pair of matching balls the third time.
Q9. 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.
Q10. What is the weight of the Ashoka Hotel?
Ans. This is one of the guesstimate examples that the interviewer will ask to test what factors to consider. While approximating such a question, you would also include the dimensions of the hotel, then you will include the weight of the material used for building the hotel. Whether there are people in the building or not, will also be important for the final approximation of the hotel’s weight.
Q11. How many people live in your housing society?
Ans. Suppose that society has only apartment-style of flats. Recall the number of apartments is numbered from 1 to 40 which means that there are 40 apartments. Each apartment block has 9 floors with 3 apartments. So, 9x3x40 = 1080 flats.
On average, Indian households have 5 members. Some apartments may be unoccupied. If assuming that 10% of apartments are unoccupied. So, the number of people living in the society will be 1080*0.9*5 =4860.
Q12. How do you fill 8 litres from 7 and 9-litre buckets?
Ans. Let us understand this step by step.
- Fill the 7L bucket completely with water.
- Pour the water from the 7L bucket into the 9L bucket. The 9L bucket now has 7L of water, and the 7L bucket is empty.
- Fill the 7L bucket completely once again.
- Carefully pour water from the 7L bucket into the 9L bucket until the 9L bucket is full. Since the 9L bucket already had 7L of water, it only needs 2L more to be full. So after this step, you will have 5L of water remaining in the 7L bucket.
- Empty the 9L bucket completely.
- Transfer the 5L of water from the 7L bucket to the 9L bucket. The 9L bucket now has 5L of water, and the 7L bucket is empty.
- Fill the 7L bucket completely again.
- Pour the water from the 7L bucket into the 9L bucket. Since the 9L bucket already has 5L of water, it can only take 4L more. This will leave you with exactly 3L in the 7L bucket.
- Empty the 9L bucket completely once more.
- Transfer the 3L of water from the 7L bucket to the 9L bucket. The 9L bucket now has 3L of water, and the 7L bucket is empty.
- Fill the 7L bucket completely again.
- Pour the water from the 7L bucket into the 9L bucket. The 9L bucket now has 3L + 7L = 10L, but since it can only hold 9L, you will have exactly 1L left in the 7L bucket.
- Empty the 9L bucket completely.
- Transfer the 1L of water from the 7L bucket to the 9L bucket. The 9L bucket now has 1L of water.
- Fill the 7L bucket completely again.
- Pour the water from the 7L bucket into the 9L bucket. The 9L bucket now has 1L + 7L = 8L of water.
Q13. 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.
Q14. 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
Tips To Answer Guesstimate Questions
These are some of the sample guesstimate questions with answers for the interview. While answering any guesstimate question, you need to keep in mind the following points:
- There is no definitive answer to such questions, only an educated guess.
- Get clarity on the conditions expected by the interviewer for each question.
- Create a flow to answer a question without trying to find a definitive answer.
- Focus on the most factual information within a question to decide a flow in the question.
- Determine the definitive or an approximate value that you already know so as to find the starting point to answer the question.
How to solve a guesstimate question?
Do not try to find the exact answer to this question. Remember that such questions do not have any fixed answer and they are meant to understand your capabilities to analyze and approximate answers. After that, try to find the pain point and available information within the question.
What type of approaches should we use to answer guesstimate questions?
To answer any guesstimate question, you can use process mapping, top-down, bottom-up and layout-centric approaches.
How can I prepare guesstimate interview questions?
To prepare for guesstimate interview questions, you need to have at least gone through a set of similar questions. These should be related to the industry in which you want to enter.
What are interviewers looking for when asking guesstimate interview questions?
Interviewers look for candidates who can think critically, use basic math and logic to solve problems, and communicate their thought process effectively. They want to assess how you handle uncertainty and ambiguity and how you approach complex problems with limited information.