PM School - How to Solve Guesstimates | Estimation Based Question in a Product Management Interview

[@pmschoolx]

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[@mayankmishra5346]

Most underrated yet most magical channel ever.

[@nikitaverma2050]

This series is Gold! Please continue to make more such videos

[@Venkat-oz4ll]

Amazing explanation. One clarification - in the guesstimate for iphones sold in India, we calculated by finding his many own an iPhone and dividing that by the lifetime of iphone. But given that a significant number of iphone owners didn't really purchase the iPhone in India but from some other country say US, Dubai etc, shouldn't that also be factored into?

[@protyaydeepshee]

very informative video, great job!

[@aishwaryaviswanadham4595]

Clarity at its peaks,keep it up.

[@vivektanirules]

This is so good, great stuff 🙌🏻

[@AnimeCricCrazySan]

Very Informative

[@bharathkumar-bp1mj]

Very informative and easy to understand

[@growingSally]

Amazing explaination 🙌

[@sunidhikashyap6199]

This video is a goldmine !!

[@tanishqbansal8374]

This series is amazing

[@hemantvardani1436]

what a beautifully simply explained video!!

[@ritesh285684]

Really helpful and helps in coming up with a well-defined approach to guesstimate problems.

[@ritesh285684]

My solution for one of the questions. Kindly provide feedback and let me know if the approach is correct. # of flights taking off daily in India Assumptions: 1. It takes 5min for a flight to take off. 2. Average no of runways in India per airport - 1.2 3. Flights are run across the day 4. 40% of the airports are commercial Solution: 8min for a flight to take off, In 1hr, 7 flights can take off In 1 hour based on average runways - 7x1.1 - 8 flights can take off per airport per hour Number of cities in India - 3000 Average # of airports per city - 0.1 Total no of airports - 300 40% of the airports are commercial while the remaining 60% of them would be for flying school and military. Total airports considered now is 300x40% = 120 Total number of flights per day = airports considered x # flights/hr x 24 = 120*8*24 = 23000 Sanity Check - 2019 stats show that 11000 flights were being flown per day.

[@pmschoolx]

Hey Ritesh, Your approach looks good. You could further break down airport timings into peak and non-peak hours, where in the peak hours you’ll have say 100% runway utilisation and in non-peak you’d have say 60% runway utilisation, and get the total number of flights taking off in a day. In a real case/interview, it’s best if you clarify your assumptions and then move into the calculations.

[@ritesh285684]

@@pmschoolx Sure, will take into consideration. Thank you for the feedback.

[@biman2057]

Did you forget to take the no of runway while calculating?

[@swaabhi]

Awesome stuff, thanks for putting this together! PS: not sure if people use bamboo sticks to brush teeth 🤣

[@arjunnagar4043]

Flawless

[@illuminati1827]

I got the correct answer using a different approach. I assumed that approx. 1% of population of India earns >=(1 lacs/month) and it would be safe to assume that only these people can afford to buy an iPhone. This gives a figure around 12 million. Considering other competitors like android, iPhone still have an edge over android for high end users, I considered that around 50% of these 12 million would be using iPhone. Now, out of these 6 million, it would be safe to assume that nearly 70% of these would be willing to upgrade phone every year. That gives around 4 million iPhones sold every year. I solved it without seeing the solution. Kindly comment whatever you think about the solution.

[@subhamgupta8719]

Why did we divide 160/ 10 for getting the iPhone users? if its 1:10, shouldn't we divide by 11 instead?

[@RanjeetMishra-bw6bh]

true. they made a mistake there.

[@tanishqbansal8374]

Nice video

[@piyabhatnagar1614]

I don't understand why would you divide 200mn by 80. Shouldn't you divide this by the split of the age groups. so 200mn divided by 2 or 3?

[@lakshmanreddy1148]

We are not aware of Population of each age group. So we assume that population of each age group is same . Let it would be x. Total age groups : 80 So , total population = 80*x. 200 mn = 80*x. x= 200mn/80

[@Dancing-Consultant]

Thank you.Session was really helpful but audio could have been better

[@pmschoolx]

We are working on it :)

[@RanjeetMishra-bw6bh]

I didn't get why we divided 200 by 80 at 5:40. Can somebody please explain?

[@RanjeetMishra-bw6bh]

soln: tot population divided by avg life expectancy gives you the births each year needed to maintain the population. which is what he multiplied by 15 to get the population to be excluded.

[@dhritigautam4941]

The solution in the cheatsheet for TV revenue in 1 year has a flaw at the very last step. The cost of TV has been assumed as 10k, whereas the final #TV sold has been multiplied by 1k to generate the revenue. Please feel free to correct it :)

[@illuminati1827]

Can you specify what cheatsheet are you talking about

[@robingupta2381]

How is occupancy related to the no. of flights taking off per day? Can you pls help?

[@yashpoddar1911]

My guesstimate gave the answer 90 lacs iphones sold in a year , and this is quite close numbers stated in some news articles Checked on google. Major factors that differed from yours was considering 15+ age percentage of population being 70% , and average lifespan of mobile phones being 3 years, and considering the fact iphone has 25% market share, I arrived the answer. Really appreciate the video, and the concise explanation.

[@harshagrawal8520]

is it a fair assumption that we took Rural to be 0 ?

[@prashantraj3613]

How to estimate macbook users in pune?

[@waz306]

Why was 2.5 multiplied by 15 ? That’s the only part I didn’t quite get ?

[@aravindvenugopal4081]

2.5M per age group. 0 - 15 Years old will not be having a phone (assumption). That is 15 age groups and hence, 15 * 2.5M = 37.5M, which he approximated to 40M people.

[@keshavbalachandar5631]

@@aravindvenugopal4081 how 15 age groups? are we grouping by 15? os it that just an assumption that we are making?

[@aravindvenugopal4081]

@@keshavbalachandar5631 considering each age as an age group, like 0-1 as one age group, 1-2 as another age group, and like that 15 age groups. To put it in a simpler way, there would be 37.5M under 0-15 age group (select any age and there would be 2.5M people having the same age)

[@keshavbalachandar5631]

@@aravindvenugopal4081 ohhh got it got it. The name “age group” confused me. I thought 1-15, 16-20 is a group. It’s actually 1, 2…. Makes sense now. Thanks a lot

[@jatinaggarwal2016]

Why 2.5 was multiplied by 15? That’s the only part I didn’t get in the video

[@piyabhatnagar1614]

Yeah me neither

[@illuminati1827]

To get the no. of users less than 15 years of age

[@sachinkesarwani3199]

Audio is not good

[@pmschoolx]

We are working on it :)

[@runitgoswami1385]

🥲I wish I can take his brain for one day