## Amazon interview question

Written on **15 February 2014, 12:18am **

**Tagged with:** amazon, interview, logic, probabilities

From Stack Exchange:

• 50% of all people who receive a first interview receive a second interview

• 95% of your friends that got a second interview felt they had a good first interview

• 75% of your friends that DID NOT get a second interview felt they had a good first interview

If you feel that you had a good first interview, what is the probability you will receive a second interview?

The easiest way (at least for me) to go is to turn those percentages into some real numbers. For instance:

– 100 friends that got a second interview; 95 of them felt that they had a good first interview

– 100 friends that did NOT get a second interview; 75 of them felt that they had a good first interview.

Now, if you ignore the fact that it’s pretty difficult to have 200 friends (let alone the fact that they all applied for a job at Amazon 🙂 ), the numbers say that:

– 95 + 75 = 170 friends had a good feeling after the first interview

– but only 95 of them had a second interview

– so the probability of you having a second interview is 95 / 170 = **0.558**.

In other words, if you felt good after the first interview, you have more than 50% chances that you get a second interview.

Image: HollywoodReporter.com

Now, if you come up with the answer 55.8% to your Amazon interviewer, I think you would get some points. But not all of them. Because in the logic below there are 2 **hidden assumptions**:

- That your group of friends is NOT representative for
**all the people**that applied - That you are representative for your group of friends

If the first assumption is false (so *your group of friends is representative for all the people that applied*), then the answer will always be 50%. It’s the first sentence of the problem: “50% of all people who receive a first interview receive a second interview”.

If the second assumption is false (so *you are NOT representative for your group of friends*) – then the 95% and 75% percents do not apply to you; so the answer is again in the first sentence of the problem.

More info on the Stack Exchange discussion.

*Written by*
**Dorin Moise**
(Published articles: 229)

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## Comments (1)

Sajithafarveen— August 11, 2015 at 13:31Many thanks for your time and efrotfs to have had these things together on this blog. Jack and i also very much appreciated your suggestions through the articles in certain things. I understand that you have quite a few demands on your program and so the fact that a person like you took the maximum amount of time just like you did to steer people like us by this article is also highly prized.