Products interview questions shared by candidates
Describe why termination is needed for CML signals2 Answers
A termination resistor is required to complete the circuit
Current mode logic (CML), or source-coupled logic (SCL), is a differential digital logic family intended to transmit data at speeds between 312.5 Mbit/s and 3.125 Gbit/s over a standard printed circuit board. The transmission is point-to-point, unidirectional and is usually terminated at the destination with 50 ? resistors to Vcc on both differential lines. CML is the physical layer used in DVI and HDMI video links, and is frequently used in interfaces to fiber optic components.
How would you design google maps?2 Answers
This question was a bit of an open ended question. We could go as low or as high in detail as I wanted to go. I chose to go a somewhat inbetween. This was probably the hardest question because I didn't really have a good idea of how it was built or what was the underlying technology underneath (don't memorize this, my interviewer said it was actually better that I didn't know so that we could discuss it). I believe what I said was that the maps would have some sort of graph data structure underneath (i think that makes the most logical sense) and that things like locations would be vertices and edges would be all the roads. After that, my memory gets a bit fuzzy but I remember talking about things like how would I speed things up? What's going on behind the scenes when people are dragging their location ? After a bunch of hints ( you can already tell that I was a bit lost), I said things like caching would make things faster, you can cache the data structures of your location on your computer instead of retrieving it from the server, when you drag the map around, basically you compute the vector of where your mouse is going and then retrieve each image in the direction of the opposite of your vector.
Since this question was directed at a product manager, presumably the interviewer was looking for a marketing answer. For example, you want a flexible user interface because there are so many types of queries which are location-dependent. And then you want to think about relevant content (emphasis on ad value) which you deliver to queries, depending on how much information is in the query and what the location maps to (and whether user is mobile). There's a paradigm from navigation systems - let users customize which types of businesses they always see on maps.
Design an elevator for a building (no specifics on what kind of building). Follow up design with two elevators and etc.2 Answers
User interaction requirements: + Aluminum and stainless steel materials/colors. + Big, bright light on ceiling. + Tactile screen with braille bumps on the sides of the tactile buttons for floors. (Accesibility) + Sound floor notifications. Efficiency: + Elevator serves users on a first-come first-served basis. Linear queue. + Gives priority to direction (up or down) indicated by current user. Other: + If floor button pushed until elevator door closes, fast mode is activated. Goes directly to desired floor without stops. (Already implemented in most elevators around the world for emergencies and fast access for local authorities). --- Extension to two elevators: (this would be a problem of concurrency) + We have a single queue with two consumers (two elevators). Elevators serve petitions on two criteria: priority of first-come-first-served and proximity of each elevator to desired destination. Final priority of petitions is based on these two aspects.
For any of the questions that start with "how would you design a..." - start with clarification of the CLIENT's NEEDS and context. Example: "how would you design an elevator?" I would first want to know more about who would be using the elevator and why. What is the purpose of the building - then go from there. The building might be a 6 story parking garage that sees high volumes of traffic at the beginning and end of the business day. The building might be a 6 unit condominium complex, a hospital, or even a furniture warehouse. Each of these types of buildings will have very different types of people/uses and therefore different requirements for an elevator.
Describe what do you write in a functional specification?3 Answers
It really depends on the type of product you're developing..and each company has a different approach on what's important in the doc. So unless you know what is important to Amazon, answering this question can be tough.
A functional spec should say what the product should do and describe inputs and outputs. The internal workings of how the product should work are ignored. Basically the functionality from a user perspective needs to be described and implementation details avoided.
All the internal workings of the system should be ignored as the user wrote above - On a high level, functional spec should contain - 1.) Use cases (including the cases where there is error) 2.) Data description (if needed) - length of input, relation between data etc. 3.) Critical business rules or algorithms (optional – depending on the product) 4.) UX design (can be a separate document) The document can also cover performance, security concerns depending on the product. A Functional spec should be as detailed as per the need of stakeholders, developer and testers. At the end of the day - PM is responsible for any misses.
3 metrics on how to measure success on a software solution that has just been implemented in the page3 Answers
it was a fallow up from a previous question... just take your time and be calm
1) # of sales before and after, obviously 2) click-through rate before and after (it tells me how intuitive the UI is for the user, as well as if there is a bug at a certain point, causing a dropoff in the CTR) 3) # of visits to the help page/FAQ page before and after (it tells me that the user might be unfamiliar with the UI)
The question is too vague, we should emphasize that the metrics are driven by the product goal. Perhaps adding an example from your experience might be good too. On high level without clear understanding of the feature that was developed on the page 1.) # of users visiting this page and who have seen this new section 2.) # of users who used any call to action in the component developed 3.) # of users who might have dropped off after certain actions. Other metrics (esp. if the page is critical) could be - 4.) Page load times with the module (it could be huge if the section in the page has multiple service calls for example)
How do you think Amazon may have come up with the $80 fee for the Amazon Prime membership program? - this is a classic pricing question.2 Answers
This is a classic pricing question. Remember customer-centric approach - willingness to pay etc.
this is mostly an expected value question. you expect, from historic data, a certain subset of people to make so many purchases from amazon. with expedited shipping, it makes sense that those people would increase their spend through amazon for secondary items such as gifts for friends/family that need to be shipped. the $80 should at least cover the expense of shipping costs, but the increase in demand and sales from that increase should even further outweigh the cost of shipping for amazon. there is also another special subset of people that may not realize their entire $80 cost to amazon, and any difference is strictly profit.
How would you make Web browsing faster?3 Answers
Obviously a very abstract question. just need to think through the user experience and possible solutions.
Not sure if this is what they were going for, but here is my approach. I would try to glean estimates of the user's next intent. E.g. if they are on a given Wikipedia page, anticipate that they might want to open the related articles or hyperlinks included in the page. Start loading these pages in the background. If you were really sophisticated at this, you could store the result of the pages loaded and keep track of what pages the users open next. This would allow you to make better predictions of what pages to load in the background for the next person.
Say DAU is increasing but MAU are decreasing (over 3 months period), how would you approach this problem and what data sets would you work with?3 Answers
Let's go over the definitions first: DAU - The measure used to find the number of *unique* daily users for the game. MAU - The measure used to find the number *unique* monthly users for the game. Since you're DAUs are going up, but you're MAU's are going down, it means that you're undergoing a large amount of churn. Essentially, lots of new people are using the app everyday, but they never come back on a month-to-month basis. Let's confine the notion of a "month" to just 3 days instead of 30. "Month 1" Day 1: 1M new people login Day 2: 1M new people login, 500k "Day 1" people login again Day 3: 1M new people login, 250k "Day 1" people login again, 500k "Day 2" people login again "Month 2" Day 1: 1.75M new people login, *nobody" from "Month 1" logs in Day 2: 250K new people login, 1.75M "Day 1" people login again Day 3: 500K new people login, 1.5M "Day 1" people login again, 250K "Day 2" people login again Already, we can see the trend occurring: Month 1 had consecutive DAUs of 1M, 1.5M, 1.75M users - and a MAU of 3M people Month 2 had consecutive DAUS of 1.75M, 2M, 2.25M - and a MAU of just 2.5M people. The game is doing much better in terms of 3-day retention despite decreasing exposure. However, when it comes to monthly retention, we're talking about 0% of users logging in the next month. You're going to have to first work entirely with retention data sets that show user session activity over the 3 month period. You're looking for retention within the month including anything from 3-day retention to 10-day retention and then figuring out when/why users are dropping off within the month. There are several factors that could lead a user to be heavily engaged for a few days and then drop the game. It could be that users are getting bored of content and are exhausting the game within a small time span. It could also mean that the game's difficulty curve is rising too steeply. Given the data we had above, you definitely know that people get "addicted" to the game for a few days and then drop off; this is very important in focusing your initial direction on what to fix. Once you know the suspects, then you can delve into more game-specific data sets such as the difficulty curve or amount of algorithmically generated content produced for users.
Just following up to my last answer above: This is just a bandage to cover up the declining MAU numbers just in case you need to meet a certain quota for your boss: You could battle decreasing MAUs by increasing the percentage of DAUs that are "new users" through increased marketing/paid installs. This way, you're not only increasing your DAUs, but you're also increasing MAUs. Be warned, however, that this isn't sustainable as you'll end up paying thousands of dollars buying installs/users that won't come back next month just to cover up a retention problem.
DAU is increasing, MAU is decreasing. * Main reason is Churn - Check your 'COHORTS'/Waterfall/Decay Analysis * Less 'Usage/engagement' * Sessions made per user gets down mostly because of the product user's using * Change/beautification in the product required * Retain with catchy Push notifications
How many hotels are their in the US2 Answers
I flubbed the algebra on this question, which doesn't look good. Make sure to pick nice round numbers to make the math easy, and pay attention to the decimal point.
51,214 see http://www.ahla.com/content.aspx?id=34706
sell me my pen. go.2 Answers
im not answering this because i know my sales practices are superior, i got the job.
This is more than a pen. This is a tool to help you write your future. With it you can agree to a new job, buy a new house, or marry your partner. Don't you want something to help you with those moments?
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