Smugglers

Question:

A group of smugglers are trapped in a forcefield. These smugglers are quite brave, that is they would attempt an escape on any positive probability of success. The smugglers are monitored by a guard who has only one bullet in his gun, but who also has perfect marksmanship skills (he never misses). A maintenance technician needs to tune up the forcefield generator, and so for one second, the forcefield is released. How can the guard still keep all the smugglers detained?

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Solution: Let’s assume the name of the three prisoners A, B and C. Then, impose three rules:
– The first one trying to escape will be shot.
– If prisoner A tries to escape at the same time as B or C, A will be shot.
– If prisoner B tries to escape at the same time as C, B will be shot.
As A knows for sure that it will be shot if he tries to escape, he will not try to escape. Since A will not try to escape, B (and then C) will also not do the same.

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