EV in my physics exam

[pzhon]

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For example, if you answer 30 questions with a single answer that has 1/3 chance of being right or two answers that have 2/3 chance between them; you expect to get 60 points with a standard deviation of 15 points either way.

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The former is like the latter with a bunch of coin-tosses for 3 points tacked on at the end, so the standard deviations are not equal.