How to approach if you are preparing for an interview?
Example Questions
- How many flights land in San Francisco International Airport every day?
- How many cars are sold per day in your country?
- How many tweets are sent per day around the world?
- Estimate the market size for baby diapers in your country
Clarify question
- Example: By diapers do you mean only baby diapers, or all diapers including dog diapers
- Example: Is the estimate for worldwide users or UK alone?
List down the basic facts / numbers related to the questions
- Example: Population of your country, Average household size
- Example: Typical email open rate, advertisement click through rate, cost per click
- Do not know some important basic fact - ask interviewer / state your assumption
Break the estimate into manageable components
- Example: Cars in London - Population of London, People per household, Cars per household
Estimate with equation
- Example: No. of households in London, “H” = Population of London / People per household
- Total Cars in London = H * Cars per household
State your assumptions
- Example: I assumed people per household in London to be 2.8
Sense Check
- You found the total cars in London to be 60 million. This is close to the population of UK.
- This is definitely an overestimate. Go back and check your assumptions, equations
- Consider some cases you have missed out
- Consider alternative approaches for a check
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