Product managers are responsible for developing and launching new products, as well as managing the lifecycle of existing products.
To be successful in this role, product managers need to be able to think critically and solve problems effectively.
A management consultant is a professional who provides expert advice and assistance to organizations to improve their performance, efficiency, and overall business strategy.
Guesstimate interview questions are a popular way for interviewers to assess the problem-solving skills of product managers or management consultants.
These questions require candidates to estimate the size of a market, the number of users for a product, or the cost of developing a new feature.
These questions can be challenging, but they are also a great opportunity to demonstrate your skills and knowledge to potential employers.
In this blog post, we will discuss the steps to answer guesstimate questions and five of the most common guesstimate interview questions for product managers or management consultants.
Steps to Answer Guesstimate Questions
Step 1: Understand the Question
Begin by making sure you fully grasp what the question is asking. If something is unclear, ask the interviewer for clarification. Don't ask for specific numerical answers; instead, seek yes-or-no type clarifications.
Step 2: Break Down the Problem
Divide the problem into smaller, manageable parts. Aim for about 4-6 steps to reach the final answer. Clearly understand the scenario and structure your approach to solving it. Use whole numbers or easy fractions for calculations, avoiding complexity.
Step 3: Determine Your Approach
Plan out your approach before diving into calculations. Ensure your method is clear and logical. Assign reasonable proportions for each segment based on your strategy. Keep communicating your thought process to the interviewer and seek their feedback.
Step 4: Start Solving
Once you've figured out your approach, start calculating. Avoid silent calculations; instead, talk through your process and ask for feedback. Stay on track with your strategy, ensuring proportions are manageable and logical.
Step 5: Double-Check and Finalize
After you've completed the calculations, review them for accuracy. Ensure everything adds up correctly. Don't worry if your final answer isn't a precise match; focus on the process and a logical final estimation.
By following these steps, you'll approach guesstimation problems systematically, making it easier to reach a reasonable and well-structured answer.
5 Most Common Guesstimate Interview Questions & Answers
1. How many elevators are required in a building of 16 floors?
Let's assume people do not wait for a lift for more than 5 minutes.
Questions and Answers to arrive at the solutions:
Q1: What is the total population of the building?
Answer: 500 People
Q2: What is the population of working people, children going to school/college, morning workout people?
Answer: 70% of the population = 350 people
Q3: Let's define peak hours: Morning 7 to 9 AM and evening 5 to 7 PM.
Assumption #1: No. of people who required a lift would be 350.
Q4: What is the lift capacity?
Answer: let's take 10 people on a single ride.
Q5: What is the max lift open and close each floor?
Answer: Open: 5 secs and closed time: 15 secs. = 15 secs
Q6: What is the total time takes of the lift to complete one ride with 15 seconds of waiting time on each floor?
Answer: 320 ((5*16) + (15*16))secs= 5.33 mins for easier calculation let's take it as 5 mins
Q7: Considering no wait time.
The required lift would be: Population at peak time/total number of people per ride = 350/10 = 35 lift if we had then no one need to wait.
However, let's assume one given point of time maximum we would have 100 people need to lift; not all 350 come at a single time; so that comes to 100/10 = 10 lifts.
If people are ready to wait for 10 mins then we need only 5 lifts for the residential building.
2. Calculate the number of queries answered by Google per second
Analysis: We'll do a top-down approach.
Global Population = say, 7.5B
Less, Geographies excluded: China, Half of Russia (people here don't use Google as their primary search engine); Less 1.5B (remaining 6B)
Less, Only 50% of people are connected to the internet (remaining 3B)
Less, Google market share with Bing, AOL, and other regional engines: Let's assume it to be about 70–80% = 75% (remaining 2.25B)
We are left with 2.2 billion people who are potentially using Google search as their primary search.
Usage Frequency
We can segment them according to their frequency of usage. I would say there are 3 types of searchers: Aggressive, Active, Passive
Passive searchers are those who don't use the internet to search daily (like old people, kids, our moms/dads, and the majority of the rural population). Assuming this type represents the majority = 50% = 1.1B people
Active people would search once a day. Assumed to be 25% of the population = 550M people
Aggressive searchers are super active searchers who might search 4-8 times a day. Assumed to be 25% of the total population = 550M people
Total searches per day= 550*1 + 550*6 = 3.8B searches per day
= 3.8B / 24 hours / 60 min / 60 sec = ~ 44,000 searches per second
3. How many iPhone users are there in India at present?
Ans. Suppose, we are considering all models of the iPhone.
There are 1.40 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 840 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 722 million. As per the statistics, the market share of the iPhone is 6%. This means there can be approximately 43 million possible iPhone users in India.
3. Estimate the number of WhatsApp Chats occurring in India daily
Estimating WhatsApp Chats in India daily
To estimate the number of WhatsApp chats occurring in India on a per-day basis, we need to consider the number of WhatsApp users in India and their chat activity across different age groups and usage levels.
Step 1: Determine the Number of WhatsApp Users in India
Let's calculate the approximate number of WhatsApp users in India using the given parameters:
Total population of India: 1.3 billion
Internet penetration: 50%
Percentage of smartphone users: 60%
Percentage of users using WhatsApp: 80%
Approximate number of WhatsApp users in India:
= 1.3 billion * 0.5 * 0.6 * 0.8
= 300 million (approx.)
Step 2: Divide WhatsApp Users by Age Groups and Usage Levels
We'll categorize WhatsApp users into different age groups and usage levels:
Age groups: 10-24, 25-35, 36-50, 51-65 years old
Usage levels: Heavy, Medium, Low
Step 3: Calculate WhatsApp Messages Sent per Day
Now, let's estimate the number of WhatsApp messages sent per day by different age groups and their respective usage levels:
For the age group 10-24 years old:
Heavy usage: 70% of 150 million WhatsApp users
Medium usage: 20% of 150 million WhatsApp users
Low usage: 10% of 150 million WhatsApp users
Total messages sent by this age group per day = 70% * 150 million + 20% * 150 million + 10% * 150 million
Similarly, calculate messages sent for the other age groups (25-35, 36-50, 51-65 years old) based on their respective usage levels.
Step 4: Total WhatsApp Messages Sent per Day in India
Now, let's calculate the total number of WhatsApp messages sent per day in India by summing up the messages sent by different age groups and their respective usage levels:
Total WhatsApp messages sent per day in India:
= Total messages sent by 10-24 years old + Total messages sent by 25-35 years old + Total messages sent by 36-50 years old + Total messages sent by 51-65 years old
= 12,111 million or approximately 12.11 billion WhatsApp messages sent per day in India.
5. Calculate the number of ATMs in India.
The population of India - 1.3 Billion
Assumption - Let the Rural: Urban split be 70:30 % of the total population.
Population Split -
Therefore, the population split approximately comes to,
Rural = 900 Million
Urban = 400 Million
Household Split -
Next, we will calculate the number of Households in India,
Assuming, there are 4 people in a household for both urban and rural,
(Ideally, we would assume, 3 for Urban and 5 for Rural)
The household split comes to,
Rural = (900 Million / 4) = 230 Million
Urban = (400 Million / 4) = 100 Million
Total number of ATM cardholders in India -
Next, let’s estimate the total number of ATM cardholders in India,
Assuming,
-
70% of Rural households have ATM cards and,
-
90% of Urban Households have ATM cards
This comes down to, (70% of 230 Million)
= 160 Million ATM cards in Rural and (90% of 100 Million)
= 90 Million ATM cards in Urban.
Now, let’s assume -
In Urban, let's say 10% of households have 2 ATMs and the rest of the 90% have 1 ATM,
= (10% * 90M)*2 + (90% * 90M)*1= 18 + 81 M = ~ 100M ATM users
In Rural, let's say 100% of households have 1 ATM,
= (100% * 160M)*1 = 160 M ATM users
Now Assuming,
1 ATM is mapped to ~500 users in the Urban area, & ~2000 users in Rural area
Total number of ATMs in Urban + Rural India =
= 100M/500 + 160M/2000
= 2,00,000 + 80,000
= 2,80,000 ATMs are there in India.
The actual number of ATMs in India is around ~2,40,000
Frequently Asked Questions:
1. What is guesstimate in product management?
During product management job interviews, you may be asked difficult questions without a definitive solution. The term "guesstimation" questions refers to this. They are designed to test your ability to think fast and make intelligent guesses
2. How do I prepare for guesstimates?
To tackle a guesstimate question, follow these three steps:
- Start by making sure you understand what the question is asking.
- Then, break big numbers into smaller parts to make them simpler.
- After that, use what you know to guess each part's size.
3. How do you answer an estimation question for a product manager?
Here's a great way to answer estimation questions well and show off your problem-solving skills:
- First, make sure you understand the question.
- List out the facts you know and any assumptions you're making.
- Come up with a straightforward solution.
- Tidy up your solution to make it clear and easy to understand.
- Think about your solution critically.
- Present your final answer with a clear explanation.
4. What is the top-down / bottom-up approach for guesstimates?
Top-down means starting with the big stuff and then focusing on the smaller details. It's like looking at a big map and then zooming in to see specific places.
Bottom-up is the other way around. You start with the small things and then put them together to understand the big picture. It's like building a tower with blocks, starting from the bottom and adding more as you go up.
5. What is guesstimate for consulting interviews?
In employment interviews, guesstimate questions are similar to a warm-up before a large test. They are typically given early on to gauge your aptitude for logical thought and numerical estimation.
They aid the interviewer in comprehending your problem-solving techniques and ability to draw accurate conclusions from the data at hand. There may be more in-depth questions later to put your knowledge to the test.
