SOLUTION: Five locks and five keys of lock fall down to the ground. Then how many tries are needed match each lock with its correct key?
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Question 850091: Five locks and five keys of lock fall down to the ground. Then how many tries are needed match each lock with its correct key?
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
take key one try it in 5 locks
you find it on last try
take key 2 and try it in 4 locks and find it on last try.
5+4
take key 3 and try it on 3 locks
now two locks
one key left and it must work.
5+4+3+2=14 tries to be sure.
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