Data Scientist Interview Questions

Tiago R. - "function findPrimes(n) { if (n < 2) return []; const primes = []; for (let i=2; i <= n; i++) { const half = Math.floor(i/2); let isPrime = true; for (let prime of primes) { if (i % prime === 0) { isPrime = false; break; } } if (isPrime) { primes.push(i); } } return primes; } `"See full answer

Bhavna S. - " with youngsuccrate as( select strftime('%m', postdate) AS postmonth, round(sum(issuccessfulpost)*1.0/count(issuccessfulpost),2)as yascrate from post where userid in (select userid from post_user where age between 0 and 18) group by post_month ), nonyoungsucc_rate as( select strftime('%m', postdate) AS postmonth, round(sum(issuccessfulpost)*1.0/count(issuccessfulpost),2)as nonyasc_rate from post where user_id in (select"See full answer

Bradley E. - "I'm pretty sure Exponent's answer is wrong. In the snippet below, they use "pl.name = 'Telephones' to attempt to filter down to the Telephone transactions, but they do this within a LEFT JOIN which means all product_lines rows are returned. > LEFT JOIN product_lines pl > ON p.productlineid = pl.id > AND pl.name = 'Telephones' Below is my solution. Also, I didn't see anywhere that said the "amount" column was in cents instead of dollars, but I still divided by 100 to be consistent with Exp"See full answer

Jaime A. - "I might be missing something but the solution, seems to be incorrect. ... , post_pairings AS ( SELECT ps.user_id, ps.postseqid AS failpostid, ps.postseqid + 1 AS nextpostid FROM post_seq AS ps WHERE ps.issuccessfulpost IS TRUE ) -- here ps.issuccessfulpost IS TRUE the condition should be FALSE -- in that way ps.postseqid is the actual failed post(failpostid) -- Additionally, at the end the join is assumming that the sequence id is going to match the post_id, wh"See full answer

Aekagra S. - "I'll approach this by asking questions and creating scenarios based on answers. If the answer to any questions points to a specific issue, I'll double down on that to understand the issue. This is more of a RCA question. First I'll quickly check Were there any recent updates released before we observed the drops? Assuming Yes, I'll check the updates released and check the test cases and testing results If the issue is identified, I will engage with the product leadership, update them and conne"See full answer

Richard B. - "Select interface, Count(case when issuccessfulpost then 1 end) as post_success, Count() as postattempt, ROUND((COUNT(CASE WHEN issuccessfulpost THEN 1 END) * 100 / COUNT()), 2) AS postsuccess_rate from post where interface like 'Iphone%' group by 1 order by postsuccessrate desc `"See full answer

Prajwal M. - "from typing import List def maxprofitgreedy(stock_prices: List[int]) -> int: l=0 # buying r=1 # selling max_profit=0 while rstock_prices[l]: profit=stockprices[r]-stockprices[l] maxprofit=max(maxprofit,profit) else: l=r r+=1 return max_profit debug your code below print(maxprofitgreedy([7, 1, 5, 3, 6, 4])) `"See full answer

Anonymous Wasp - "I was able to answer this question and the follow-up questions as well"See full answer

Kanishkan V. - "I responded with a project that I was a part of during my capstone class. I described how I used HTML, Python, and PostGRESQL in conjunction to create a functioning website using SCRUM."See full answer

Farza S. - "It is the smallest level of significance at which the null hypothesis gets rejected"See full answer

Sangeeta P. - "A/B testing is used when one wishes to only test minor front-end changes on the website. Consider a scenario where an organization wishes to make significant changes to its existing page, such as wants to create an entirely new version of an existing web page URL and wants to analyze which one performs better. Obviously, the organization will not be willing to touch the existing web page design for comparison purposes. In the above scenario, performing Split URL testing would be beneficial. T"See full answer

Anonymous Roadrunner - "from typing import List def two_sum(nums: List[int], target: int) -> List[int]: prevMap = {} for i, n in enumerate(nums): diff = target - n if diff in prevMap: return [prevMap[diff], i] else: prevMap[n] = i return [] debug your code below print(two_sum([2, 7, 11, 15], 9)) `"See full answer

Marcos G. - "with my_table as (select * , rownumber() over(order by customerid) as row_index from customers) select customer_id, customer_name from my_table where row_index % 3 = 0"See full answer

Laura U. - "productssold = set(transactions['productid']) unsoldproducts = products.loc[~products['id'].isin(productssold)] return unsold_products[["id", "name", "stock"]] `"See full answer

Alvin P. - "WITH high_score AS( SELECT player_id, MAX(gamescore) AS maxscore FROM scores GROUP BY player_id ), rankings AS( SELECT p.player_name, p.team_id, max_score, DENSERANK() OVER(PARTITION BY p.teamid ORDER BY h.maxscore DESC) AS scorerank FROM high_score AS h JOIN players AS p USING(player_id) ) SELECT team_id, player_name, max_score FROM rankings WHERE score_rank <= 2 GROUP BY teamid, playername O"See full answer