CMI2011-A-06

Question

A valuable sword belonging to the Grand King was stolen, and the three suspects were Ibn, Hasan, and Abu. Ibn claimed that Hasan stole it, and Hasan claimed that Abu stole it. It was not clear that one of them stole it, but it was later learnt that no innocent person had lied. It was also learnt that the sword was stolen by only one person.
Who stole the sword?

• A. Ibn
• B. Hasan
• C. Abu
• D. None of them

Answer 1

"no innocent person had lied"

Ibn and Hasan made the claims. 

If Ibn is culprit then he must be lying but then why Hasan is lying? Our assumption of Ibn as culprit is wrong.

Now assuming Abu as culprit, both Hasan and Ibn must be pointing towards same person because they are saying the truth but its not the case and our assumption of Abu being the culprit is also wrong.

Assuming Hassan as culprit he is lying and Iba is pointing towards Hasan as Iba is innocent. 

Hasan stole the sword.

Answer 2

Answer B)Hasan

No innocent person lied , means here no one lied

As Ibn claimed it was first stolen by Hasan and from Hasan it is stolen Abu

So, first person who steal it is Hasan