Google PM interview questions - how many computers does Google own?

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cyberpro

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Nov 9, 2017 13 Comments

How would you answer this question. The number of users laptops could be easily estimated. How about the servers ?

Would you calculate for each product ? Search, Youtube, Gmail - can't possibly do that in the interview.

How would you calculate number of users per server and number of simultaneous users served etc ?

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TOP 13 Comments
  • Amazon LMbC33
    About tree fiddy
    Nov 9, 2017 0
  • Amazon / Eng (;,;)
    I thought brain teasers were forbidden at Google?
    Nov 10, 2017 2
    • Facebook / Eng ixUY64
      This isn't a brain teaser, it's a standard PM "estimation" question.
      Nov 10, 2017
    • Amazon LMbC33
      Can they Google the answer?
      Nov 10, 2017
  • Amazon MsPeculiar
    1. Define computer. For estimation purposes, will assume that the question is asking about personal computers, nor servers or VMs. Will assume this is limited to desktop and laptop, not mobile.

    2. Identify where personal computers live across Google and assign number estimates: each employee desk (remote and in office), reception desks, security desks, backup storage (old employee computers), devo devices, IT services, extra supplies for normal business needs (assume buffer of 10% of other computers).

    3. Add it up.

    What did I forget? Critique my answer please.
    Nov 10, 2017 1
    • New / Product
      cyberpro

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      MsPeculiar - I was thinking the same but what if they are servers? How would you even break down the problem. If I have to calculate the servers I can take the top 10 Google products - Gmail, YouTube, maps, search, Google+, Google drive/docs and calculate the number of users and compute+space for those users.

      Eg: Gmail has 1B users on average taking 7GB storage. YouTube has 1B users most viewing but maybe 10B content at 100mb/video.

      What do you think about search. How would I break down the server requirements to run search ? Number if internet pages to index? I could throw a 10trillion number there and say 100kb/page of bandwidth consumption and 1kb index storage. What else ?
      Nov 12, 2017
  • Microsoft wxyz99
    Own, or use? Is a VM a computer? What about leased equipment?
    Nov 10, 2017 0
  • Google / Eng UUKg61
    Look for “Fermi approximation” and you would know how to answer this.
    Nov 10, 2017 2
    • Amazon LMbC33
      Sure, but anyone doing a Fermi approximation in real life would seek actual data for at least some of the terms. Like, "how many people work for Google", or "how many searches were performed last year" and then likely validate assumptions about tps by looking at comparable systems.

      So it makes a shitty interview question unless you're providing them an internet enabled computer to go and do some research on. Which everyone would use Google for, ironically.

      Even ten or twenty minutes of searching for data will dramatically improve the Fermi estimation over spitballing it at a whiteboard.
      Nov 10, 2017
    • Microsoft cout<<
      Yes. Being able to do a quick back of the envelope estimation is valuable for day to day. Of course if you need a specific count you’ll look it up. What the questions answers is
      1. Will you identify the scope of what you need to count (or leave out whole segments)?
      2. Can you get to a General magnitude?If not, how can you be trusted to know when numbers seem off or for day to day scale considerations.

      There isn’t an interviewer out there who expects the right answer — they expect the right classification of what should be estimated and that you have a basic sense magnitude /basic math.
      Nov 11, 2017
  • New / Product
    cyberpro

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    @jeje - read the question. This is for an interview questions. So yes you need to calculate.
    Nov 12, 2017 0
  • Zillow Group jeje
    Answer : Why should I calculate, will look at counters or will ask devs to create one
    Nov 10, 2017 0
  • New / Product
    cyberpro

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    Good points. Probably use. But could be own.
    Nov 10, 2017 0

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