Four sealed boxes sit before you; exactly one hides \(\$100\), the other three are empty. You may open boxes one at a time, stopping as soon as you find the cash. Each box you open costs \(X\) dollars, and that includes the box with the money: you must open it to collect the \(\$100\). So if the first three boxes are empty, you still pay to open the fourth.
What price \(X\) makes the game fair (i.e., zero expected profit for both sides)?
Reported at 2 firmsSIG · WincentI’ve seen this in an interviewI’ve seen this
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