Data Scientist脑筋急转弯&统计学面试题总结


Data Science Puzzles-Brain Storming/ Puzzle Questions asked in Data Science Job Interviews 1) How many Piano Tuners are there in Chicago? To solve this kind of a problem, we need to know –

How many Pianos are there in Chicago? How often would a Piano require tuning? How much time does it take for each tuning?

We need to build these estimates to solve this kind of a problem. Suppose, let’s assume Chicago has close to 10 million people and on an average there are 2 people in a house. For every 20 households there is 1 Piano. Now the question how many pianos are there can be answered. 1 in 20 households has a piano, so approximately 250,000 pianos are there in Chicago.

Now the next question is-“How often would a Piano require tuning? There is no exact answer to this question. It could be once a year or twice a year. You need to approach this question as the interviewer is trying to test your knowledge on whether you take this into consideration or not. Let’s suppose each piano requires tuning once a year so on the whole 250,000 piano tunings are required.

Let’s suppose that a piano tuner works for 50 weeks in a year considering a 5 day week. Thus a piano tuner works for 250 days in a year. Let’s suppose tuning a piano takes 2 hours then in an 8 hour workday the piano tuner would be able to tune only 4 pianos. Considering this rate, a piano tuner can tune 1000 pianos a year.

Thus, 250 piano tuners are required in Chicago considering the above estimates.

2) There is a race track with five lanes. There are 25 horses of which you want to find out the three fastest horses. What is the minimal number of races needed to identify the 3 fastest horses of those 25? Divide the 25 horses into 5 groups where each group contains 5 horses. Race between all the 5 groups (5 races) will determine the winners of each group. A race between all the winners will determine the winner of the winners and must be the fastest horse. A final race between the 2nd and 3rd place from the winners group along with the 1st and 2nd place of thee second place group along with the third place horse will determine the second and third fastest horse from the group of 25.

3) Estimate the number of french fries sold by McDonald's everyday. 4) How many times in a day does a clock’s hand overlap? 5) You have two beakers. The first beaker contains 4 litre of water and the second one contains 5 litres of water.How can you our exactly 7 litres of water into a bucket? 6) A coin is flipped 1000 times and 560 times heads show up. Do you think the coin is biased? 7) Estimate the number of tennis balls that can fit into a plane. 8) How many haircuts do you think happen in US every year?

9) In a city where residents prefer only boys, every family in the city continues to give birth to children until a boy is born. If a girl is born, they plan for another child. If a boy is born, they stop. Find out the proportion of boys to girls in the city.

Probability and Statistics Interview Questions for Data Science

There are two companies manufacturing electronic chip. Company A is manufactures defective chips with a probability of 20% and good quality chips with a probability of 80%. Company B manufactures defective chips with a probability of 80% and good chips with a probability of 20%.If you get just one electronic chip, what is the probability that it is a good chip? Suppose that you now get a pack of 2 electronic chips coming from the same company either A or B. When you test the first electronic chip it appears to be good. What is the probability that the second electronic chip you received is also good?

A coin is tossed 10 times and the results are 2 tails and 8 heads. How will you analyse whether the coin is fair or not? What is the p-value for the same? Continuation to the above question, if each coin is tossed 10 times (100 tosses are made in total). Will you modify your approach to the test the fairness of the coin or continue with the same?

An ant is placed on an infinitely long twig. The ant can move one step backward or one step forward with same probability during discrete time steps. Find out the probability with which the ant will return to the starting point.

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