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Roll three times, keep the best, price it

Asked at Jane Street, DRW

You roll a fair six-sided die three times and get paid the highest face among the three rolls, in dollars. Unlike the keep-the-last game, a good early roll is never thrown away: you always end up with the maximum.

What is the fair value of this game?

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Since you keep the best, there is no stopping decision at all, just roll all three. You need E[max]E[\max] of three independent dice. It is easiest to compute via P(maxk)=(k/6)3P(\max \le k) = (k/6)^3.

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