<t>QuoteOriginally posted by: ymousOK, I get the same answer, but just wanted to provide more rigorous reasoning.If s < S/2 after opening n boxes, then the expected gain for (n+1)th box is (S - s) / (N - n) - s / (N - n) = (S - 2s) / (N - n), which is already positive. So one must continue regardles...