SOLUTION: Samir has a combination lock with numbers from 1 to 30. This is the type of lock that requires three numbers to be opened: turn right for the first number, left for the second numb
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Question 1117550: Samir has a combination lock with numbers from 1 to 30. This is the type of lock that requires three numbers to be opened: turn right for the first number, left for the second number, and right for the third number. Samir remembers the first two numbers, and they are not equal; but he can't remember which one is first and which is second. Also, he has forgotten the third number. What is the greatest number of tries he must make to open the lock?
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
Arbitrarily choose one of the first two numbers as #1. Attempt to open the lock with the first two numbers in the arbitrarily chosen order and do this once for each possible 3rd number. If the order of the first two numbers is incorrect, this will fail 30 times. Then reverse the order of the first two numbers and try again once for each possible 3rd number. Worst case, this will fail 29 times and be successful on the 30th try. So the absolute maximum number of attempts, given that he never loses his place requiring him to start over, is 59 failures followed by 1 success. 60 tries.
John
My calculator said it, I believe it, that settles it
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