Let’s consider a scenario. Suppose Akshay is interviewing for a product manager role with Amazon.
Rajat: Hi! Good morning.
Akshay: Good Morning! Pleased to meet you. (It’s imperative to greet the interviewer in the beginning. This builds a cordial relationship between the two of you.)
Rajat: Nice to meet you too! You are interviewing for the position of product manager - Apparel with Amazon. Let’s start with a small estimation problem.
Akshay: Yes.
Rajat: Let’s proceed, then.
Akshay: Sure!
Rajat: How many people wear red in Delhi on a typical day?
Akshay: Before proceeding, I wish to seek certain clarifications so that I can solve this problem efficiently.
(Before giving an answer, it is important to understand the question and seek necessary clarifications, as well as the interviewer’s views.)
Rajat: Yes, go ahead.
Akshay: I have two questions.
- Please explain the term “wear red”.
- Is Delhi to be considered as Delhi city or Delhi NCR region? (These are two questions that, if not answered, would take the problem in a different direction.)
Rajat: You can assume that any piece of red clothing on the person means wearing red. Take only Delhi into consideration before proceeding further.
Akshay: Thank you. Can you please give me a minute to put together my thoughts before I move on to the next steps?
(After receiving the necessary information, requesting a bit of time to collate the given information and thinking about the necessary information gives the interviewer a positive impression. Also, it opens up a chance for the interviewer to give you a direction for proceeding further.)
Akshay: I will begin with categorising the Indian population into the urban and rural sectors. Assuming a certain proportion of the Indian urban population resides in Delhi, I will further categorise it by assuming a viable gender ratio. Further, assuming that the use of red clothes amongst the proportion of the female population in Delhi is higher than that of the male population, I will carry out the calculation using the necessary computational method.
Rajat: Carry on!
Akshay: I would further detail the calculations step by step:
- I will round out the Indian population at 1.3 billion to make the calculation easier and simpler.
- The population divide (urban: rural) is assumed to be 30:70
- The Indian urban population is (urban proportion × Indian population) = 0.3 × 1.3 billion = 0.39 billion
- Major metros (Delhi, Mumbai, Kolkata and Chennai) comprise approximately 20% of the total Indian urban population
- The urban population in the major metro cities is (0.2 × Indian urban population) = 0.2 × 0.39 billion, which is 78 million
- With Delhi assumed to host 25% of the major metro urban population,
- The Indian urban population residing in Delhi is computed as (Urban population in major metro cities × 0.25) = 78 million × 0.25, approximated to be 19 million
- Assuming the gender ratio in Delhi to be equally distributed (50-50 split between men and women), I will compute the number of males and females in Delhi
- The number of males in Delhi is (Population of Delhi × 0.5) = 19 million × 0.5 = 9.5 million
- The number of females in Delhi is (Population of Delhi × 0.5) = 19 million × 0.5 = 9.5 million
- As mentioned earlier, I will assume that the proportion of the female population wearing red would be slightly more than that of the male population. Assuming the proportion of male and female population wearing red to be 10% and 15% respectively, the subsequent computation would be:
- The male population in Delhi wearing red is (0.10 × Number of males in Delhi) = 0.10 × 9.5 million = 0.95 million
- The female population in Delhi wearing red is (0.15 × the number of females in Delhi ) = 0.15 × 9.5 million = 1.42 million, approximated to be 1.4 million
- The total population wearing red in Delhi is (0.95 million + 1.4 million), which comes to a total of 2.35 million (Always state your assumptions clearly in every step — E.g. Assuming the number of the male and female population in Delhi wearing red clothes to be 10% and 15% respectively.)
So I would like to conclude the discussion by saying that 2.35 million people in Delhi wear red on a typical day. (The guesstimate should be concluded by summarising the solution and the final answer)
Rajat: That’s great! Thank you for your time. Have a nice day.
Akshay: Thank you for your time too! It was a pleasure meeting you! Have a great day. (Close the interview with a pleasant greeting to leave a positive impression)
Another Approach
This guesstimate can also be approached by considering the following parameters:
- Climate:
- In winters, people tend to wear red sweaters/jackets/hoodies/scarves in addition to red clothes
- In summers, because of the severe heat, people tend to wear light-coloured clothes
- Special occasions such as festivals and election rallies where the usage of red clothing could be higher
Please note that your focus should be on how you approach the problem rather than the numbers involved. Read some more articles of guesstimates from the link given below:
- How to solve guestimates with the help of solved examples - Link