The police rounded up 35 people suspected of robbing a bank. Each person was assigned a number from 1 to 35. After a short investigation, three of them were arrested, numbers #14, #17 and #26. They made the following statements under intensive questioning: #14: I'm innocent. #17: I'm innocent. #26: #14 is guilty. If only one of these statements is true, who robbed the bank?

Question

Mathematics

Charity Frazier

14 October, 20:18

The police rounded up 35 people suspected of robbing a bank. Each person was assigned a number from 1 to 35. After a short investigation, three of them were arrested, numbers #14, #17 and #26. They made the following statements under intensive questioning: #14: I'm innocent. #17: I'm innocent. #26: #14 is guilty. If only one of these statements is true, who robbed the bank?

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Libby Fuller · Answer 1

If only one of these statements is true, #17 robbed the bank.

Step-by-step explanation:

1st Scenario: #26 tells the truth

If #26 is telling the truth, that means #14 is guilty and, consequently, lying. However, that would also mean that #17 is telling the truth and then more than one statement would be true.

2nd Scenario: #17 tells the truth

If #17 is telling the truth, #17 is innocent, but then again either #26 or #14 are lying and two statements would be true.

3rd Scenario: #14 tells the truth

If #14 is telling the truth, #14 is innocent and, consequently, #26 is lying. That leaves us with #17 claiming innocence, but since only #14 can be telling the truth, #17 is lying and robbed the bank.