
Jane Street Guide to Probability and Financial Markets [pdf] - bookofjoe
https://www.janestreet.com/static/pdfs/trading-interview.pdf
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Bostonian
Their answer to "Q: What's the probability that when we roll 2 d6s and add up
the results, we get 7?" could be shorter. It is 1/6 because after the first
die produces a number from 1 to 6, there is exactly a 1/6 chance that the
second die will produce a number giving a sum of 7. The probability of getting
a sum of 6 from two dice is 5/6*1/6 = 5/32 using similar logic.

