Fifty Peeks at a Hundred Drawers

A firm's badge room has 100 100 numbered drawers holding the 100 100 interns' numbered badges in a uniformly random one-per-drawer arrangement. Each intern enters alone and may open at most 50 50 drawers seeking their own badge; drawers are shut again before the next intern, and no communication is allowed once searches begin. The cohort graduates only if every intern finds their own badge. Opening 50 50 random drawers per intern succeeds with probability (1/2)100 (1/2)^{100} . Find a strategy that succeeds with probability greater than 30% 30\% , and compute that probability.

Answer

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