Data Interview Questions

132,700 data interview questions shared by candidates

Given a table with columns country (with two-letter country abbreviation), count of requests sent, percentage of requests sent failed, condense down to this data grouped by country: country (one row per country), total count of requests sent, total count of requests sent failed.
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Data Scientist

Interviewed at Meta

3.6
Apr 29, 2019

Given a table with columns country (with two-letter country abbreviation), count of requests sent, percentage of requests sent failed, condense down to this data grouped by country: country (one row per country), total count of requests sent, total count of requests sent failed.

Given a multi-step product feature, write SQL to see how well this feature is doing (loading times, step completion %). Then use Python to constantly update average step time as new values stream in, given that there are too many to store in memory.
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Data Engineer

Interviewed at Meta

3.6
Apr 30, 2018

Given a multi-step product feature, write SQL to see how well this feature is doing (loading times, step completion %). Then use Python to constantly update average step time as new values stream in, given that there are too many to store in memory.

SQL: 1. Percentage increase in revenue compared to promoted and non-promoted products. 2. Products classes that has the highest transactions 3. Count of Customers who bought 2 items type (A,B) 4. Don't remember Python: 1. Average length of letters to words. 2. Parse an ip address (This is a favourite FB question) 3. [[A],[A,B],[A,C],[B,D],[C,A]] -- Find the alphabet with highest neighbors? -- (Wasnt able to solve because of time limit but the interviewer was like I get what I want to convey.. I gave her an algo of what I would I have done)
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Data Engineer

Interviewed at Meta

3.6
Sep 21, 2018

SQL: 1. Percentage increase in revenue compared to promoted and non-promoted products. 2. Products classes that has the highest transactions 3. Count of Customers who bought 2 items type (A,B) 4. Don't remember Python: 1. Average length of letters to words. 2. Parse an ip address (This is a favourite FB question) 3. [[A],[A,B],[A,C],[B,D],[C,A]] -- Find the alphabet with highest neighbors? -- (Wasnt able to solve because of time limit but the interviewer was like I get what I want to convey.. I gave her an algo of what I would I have done)

business sense: There are two types of cars A and B. The number of people in US who use A and B are the same. They drive the same distances each month. Now there are two new technologies, X and Y (of equal cost). If apply X, mpg of A would increase from 50 mpg to 75 mpg; If apply Y, mpg of B would increase from 10 mpg to 11 mpg. The goal is to decrease the dependence on foreign oil, or to decrease the consumption of gasoline. Question: which technology would you apply? Follow up question: after applying the technology of your choice, assume there's money available for research on new technology, which car would you choose to conduct research on?
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Data Scientist

Interviewed at Meta

3.6
Jan 7, 2015

business sense: There are two types of cars A and B. The number of people in US who use A and B are the same. They drive the same distances each month. Now there are two new technologies, X and Y (of equal cost). If apply X, mpg of A would increase from 50 mpg to 75 mpg; If apply Y, mpg of B would increase from 10 mpg to 11 mpg. The goal is to decrease the dependence on foreign oil, or to decrease the consumption of gasoline. Question: which technology would you apply? Follow up question: after applying the technology of your choice, assume there's money available for research on new technology, which car would you choose to conduct research on?

In python code, given a json object with nested objects, write a function that flattens all the objects to a single key value dictionary. Do not use the lib that actually performs this function. { a:{b:c,d:e} } becomes {a_b:c, a_d:e} ( not, a:"b:c,d:e" }
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Data Engineer

Interviewed at Amazon

3.5
Apr 29, 2020

In python code, given a json object with nested objects, write a function that flattens all the objects to a single key value dictionary. Do not use the lib that actually performs this function. { a:{b:c,d:e} } becomes {a_b:c, a_d:e} ( not, a:"b:c,d:e" }

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