"Narrow down on a person (born in city childhood - school - college - work - retirement)
Age:
0-5 = ignoring travel for this part (might travel with parents)
5-19 = weekdays school, weekends outings
School distance 5 km , total = 10km (to & fro) (4 intersections * 1min(time spent) = 4 min/ day)
52 x 5 x 4 = 1040 mins ~ 15 hrs
15 * 14 yrs = 210 hrs
Weekends 52 x 2 = 104 days * 0.3 = 30 days
Trips = 10 km (8 intersections * 1min(time spent) = 8 mins)
30 x 8 ="
Rev - "Narrow down on a person (born in city childhood - school - college - work - retirement)
Age:
0-5 = ignoring travel for this part (might travel with parents)
5-19 = weekdays school, weekends outings
School distance 5 km , total = 10km (to & fro) (4 intersections * 1min(time spent) = 4 min/ day)
52 x 5 x 4 = 1040 mins ~ 15 hrs
15 * 14 yrs = 210 hrs
Weekends 52 x 2 = 104 days * 0.3 = 30 days
Trips = 10 km (8 intersections * 1min(time spent) = 8 mins)
30 x 8 ="See full answer
"I'm a bit confused - The $40B hrs is the total time spent commuting to work, correct? Whereas the question asks "hours lost ... in traffic". Is the answer not correct then?"
Lucy Y. - "I'm a bit confused - The $40B hrs is the total time spent commuting to work, correct? Whereas the question asks "hours lost ... in traffic". Is the answer not correct then?"See full answer
"Clarifying and Assumptions
When we say New York City, does this mean just Downtown New York or also the suburbs? Assumption: It means Downtown New York only.
Is the bike-sharing service like Uber, where people share their own bikes, or is it a service run by a company with bike stands on street corners? Assumption: It’s run by a private company with bike stands on street corners.
Will the bike-sharing service start as free, or will we charge people from the beginning?"
Darpan D. - "Clarifying and Assumptions
When we say New York City, does this mean just Downtown New York or also the suburbs? Assumption: It means Downtown New York only.
Is the bike-sharing service like Uber, where people share their own bikes, or is it a service run by a company with bike stands on street corners? Assumption: It’s run by a private company with bike stands on street corners.
Will the bike-sharing service start as free, or will we charge people from the beginning?"See full answer
"Questions:
Are these bikes for personal or commercial use? Or both?
For commuting, or should we also include recreational bikes (e.g. mountain bikes?)
Should we include stationary exercise bikes, or only those used outside?
E-bikes and motorcycles?
Are we counting children, or just adults?
Should we factor in whether the individual has purchasing power to purchase a new bike? What about renting a bike?
Assumptions:
Assuming we are sizing the market for personal commuter bicycles f"
Chelsea F. - "Questions:
Are these bikes for personal or commercial use? Or both?
For commuting, or should we also include recreational bikes (e.g. mountain bikes?)
Should we include stationary exercise bikes, or only those used outside?
E-bikes and motorcycles?
Are we counting children, or just adults?
Should we factor in whether the individual has purchasing power to purchase a new bike? What about renting a bike?
Assumptions:
Assuming we are sizing the market for personal commuter bicycles f"See full answer
Product Manager
Estimation
🧠Want an expert answer to a question? Saving questions lets us know what content to make next.
"First I would like to ask you some clarifying questions.
Timeframe: do we consider a single given day? YES
What is the definition of jogger? Running, not walking
Is there a minimum distance? NO
Do you count only the distance within the perimeter of central park or also the miles getting in and out of CP to my start location? ONLY CP
Great, I would like to structure the problem this way.
\# of aggregated miles run by jogger in a day in CP = # of joggers per day * av"
Fabio E. - "First I would like to ask you some clarifying questions.
Timeframe: do we consider a single given day? YES
What is the definition of jogger? Running, not walking
Is there a minimum distance? NO
Do you count only the distance within the perimeter of central park or also the miles getting in and out of CP to my start location? ONLY CP
Great, I would like to structure the problem this way.
\# of aggregated miles run by jogger in a day in CP = # of joggers per day * av"See full answer
"Clarifications: Is it passenger/cargo/defense
Answer: Passenger
Is it direct or stops included - Direct
Last I read London had 80 M passengers annually
Per month - 6.7 M
Per Day - 220 K
Assumption here - London is a hub and it has flights to all continents. Assumptions are the split below
Flights to Europe -- 30%
Flights to USA -- 20%
Flights to Asia -- 30%
Flights to Africa -- 10%
Flights to Australia -- 10%
Dubai is part of Asia - 30% of 220 K is 66K
Within Asia - Passeng"
Ramesh Y. - "Clarifications: Is it passenger/cargo/defense
Answer: Passenger
Is it direct or stops included - Direct
Last I read London had 80 M passengers annually
Per month - 6.7 M
Per Day - 220 K
Assumption here - London is a hub and it has flights to all continents. Assumptions are the split below
Flights to Europe -- 30%
Flights to USA -- 20%
Flights to Asia -- 30%
Flights to Africa -- 10%
Flights to Australia -- 10%
Dubai is part of Asia - 30% of 220 K is 66K
Within Asia - Passeng"See full answer
"Clarifying and Assumptions
Is there any specific geography we need to restrict to? Assumption: Total worldwide.
Is there any specific segment we need to restrict to? Assumption: All segments.
Number of users
Total worldwide users: 300,000,000
Storage per user
Slice the users into 3 segments.
Low users 80%
Free tier 2 GB per user available
Using the 80-20 rule for segmentation.
Medium users 10%
Basic paid tier 2 TB per user available
Usi"
Darpan D. - "Clarifying and Assumptions
Is there any specific geography we need to restrict to? Assumption: Total worldwide.
Is there any specific segment we need to restrict to? Assumption: All segments.
Number of users
Total worldwide users: 300,000,000
Storage per user
Slice the users into 3 segments.
Low users 80%
Free tier 2 GB per user available
Using the 80-20 rule for segmentation.
Medium users 10%
Basic paid tier 2 TB per user available
Usi"See full answer
"Solution:
World population = 8B
Assuming 10% of world population does not use detergent( using only soap or using only water)
Remaining population = 90/100 * 8B = 7.2B ~ 7B
Diving the users into 3 categories
Users who wash everyday
Users who wash twice a week
Users who wash once a week
Wash everyday --- Wash twice a week --- Wash once a week
Used clothes < Used clothes < Used clothes
5gm --- 10gm --- 15gm (Detergent used"
Reshma R. - "Solution:
World population = 8B
Assuming 10% of world population does not use detergent( using only soap or using only water)
Remaining population = 90/100 * 8B = 7.2B ~ 7B
Diving the users into 3 categories
Users who wash everyday
Users who wash twice a week
Users who wash once a week
Wash everyday --- Wash twice a week --- Wash once a week
Used clothes < Used clothes < Used clothes
5gm --- 10gm --- 15gm (Detergent used"See full answer
"Assume that US and Japan are exactly opposite to each other. If a flight takes 18 hrs to travel between US and Japan and it moves at approx 600km/hr, then the distance covered is 10,800 Km. This constitutes the semi arc of the circle, so we will double is to calculate full circumference which will be 21,600 km."
Joohi M. - "Assume that US and Japan are exactly opposite to each other. If a flight takes 18 hrs to travel between US and Japan and it moves at approx 600km/hr, then the distance covered is 10,800 Km. This constitutes the semi arc of the circle, so we will double is to calculate full circumference which will be 21,600 km."See full answer
"Since I am residing in Bangalore, I will consider the Bengaluru airport. The airport has 2 terminals. I am going to consider the security scan done at both the terminals for the estimation.
Does it include security scans for both international and domestic flights? --> Both
The airport crew members and pilots also go through the security scan. So, should I include only them as well or only the passengers in my calculation? --> Only the passengers
Number of people going through the security scan"
Sangeeta P. - "Since I am residing in Bangalore, I will consider the Bengaluru airport. The airport has 2 terminals. I am going to consider the security scan done at both the terminals for the estimation.
Does it include security scans for both international and domestic flights? --> Both
The airport crew members and pilots also go through the security scan. So, should I include only them as well or only the passengers in my calculation? --> Only the passengers
Number of people going through the security scan"See full answer
"👇 Your feedback is very much appreciated 👇
Clarifying Questions
Should we look at it worldwide or in the USA only?
Should we consider all Slack messages? ones that are sent in business-owned workspaces? ones that are sent in other types of communities?
We'll give numbers for this scope:
worldwide
all messages
Approach:
Nb of users x Nb messages sent by user per hour x Nb hours worked per day
Nb of users: 10M
Nb of messages per hour: 10
Nb of hours worked per day: 8
So an"
Julien C. - "👇 Your feedback is very much appreciated 👇
Clarifying Questions
Should we look at it worldwide or in the USA only?
Should we consider all Slack messages? ones that are sent in business-owned workspaces? ones that are sent in other types of communities?
We'll give numbers for this scope:
worldwide
all messages
Approach:
Nb of users x Nb messages sent by user per hour x Nb hours worked per day
Nb of users: 10M
Nb of messages per hour: 10
Nb of hours worked per day: 8
So an"See full answer
"This is another Fermi problem — an estimation or approximation problem with limited information and back-of-the-envelope calculations. There's no right answer: interviewers want to understand how you think and how well you can explain your reasoning, rather than what you already know.
Recall the formula for Fermi problems:
Ask clarifying questions
Catalog what you know
Make equation(s)
Think about edge cases to add to equation
**Breakdown components of your"
Exponent - "This is another Fermi problem — an estimation or approximation problem with limited information and back-of-the-envelope calculations. There's no right answer: interviewers want to understand how you think and how well you can explain your reasoning, rather than what you already know.
Recall the formula for Fermi problems:
Ask clarifying questions
Catalog what you know
Make equation(s)
Think about edge cases to add to equation
**Breakdown components of your"See full answer
"Clarifications:
Do we consider window for any building or only residences? I will ignore windows in cars for complexity reasons.
Pardon my ignorance for not knowing the size and population of Tehran, Would you mind sharing some inputs or is it okay if pick some Randoms?
Analysis:
Tehran is ~300 sq. miles in terms of land area with an overall population of 9 MM with an average 3.5 members per household.
_I will be moving with windows for residences only and then gut check my response"
RockyBalboa - "Clarifications:
Do we consider window for any building or only residences? I will ignore windows in cars for complexity reasons.
Pardon my ignorance for not knowing the size and population of Tehran, Would you mind sharing some inputs or is it okay if pick some Randoms?
Analysis:
Tehran is ~300 sq. miles in terms of land area with an overall population of 9 MM with an average 3.5 members per household.
_I will be moving with windows for residences only and then gut check my response"See full answer
"This is a Fermi problem — an estimation or approximation problem with limited information and back-of-the-envelope calculations. There's no right answer: interviewers want to understand how you think and how well you can explain your reasoning, rather than what you already know.
Recall the formula for Fermi problems:
Ask clarifying questions
Catalog what you know
Make equation(s)
Think about edge cases to add to equation
**Breakdown components of your equat"
Exponent - "This is a Fermi problem — an estimation or approximation problem with limited information and back-of-the-envelope calculations. There's no right answer: interviewers want to understand how you think and how well you can explain your reasoning, rather than what you already know.
Recall the formula for Fermi problems:
Ask clarifying questions
Catalog what you know
Make equation(s)
Think about edge cases to add to equation
**Breakdown components of your equat"See full answer
"This is a Fermi problem — an estimation or approximation problem with limited information and back-of-the-envelope calculations. There's no right answer: interviewers want to understand how you think and how well you can explain your reasoning, rather than what you already know.
Recall the formula for Fermi problems:
Ask clarifying questions
Catalog what you know
Make equation(s)
Think about edge cases to add to equation
**Breakdown components of your equat"
Exponent - "This is a Fermi problem — an estimation or approximation problem with limited information and back-of-the-envelope calculations. There's no right answer: interviewers want to understand how you think and how well you can explain your reasoning, rather than what you already know.
Recall the formula for Fermi problems:
Ask clarifying questions
Catalog what you know
Make equation(s)
Think about edge cases to add to equation
**Breakdown components of your equat"See full answer
"This is another Fermi problem — an estimation or approximation problem with limited information and back-of-the-envelope calculations. There's no right answer: interviewers want to understand how you think and how well you can explain your reasoning, rather than what you already know.
Recall the formula for Fermi problems:
Ask clarifying questions
Catalog what you know
Make equation(s)
Think about edge cases to add to equation
**Breakdown components of your"
Exponent - "This is another Fermi problem — an estimation or approximation problem with limited information and back-of-the-envelope calculations. There's no right answer: interviewers want to understand how you think and how well you can explain your reasoning, rather than what you already know.
Recall the formula for Fermi problems:
Ask clarifying questions
Catalog what you know
Make equation(s)
Think about edge cases to add to equation
**Breakdown components of your"See full answer