Coburg Banks | Multi-sector UK recruitment agency

Brainteaser Answer 9

By Mark Wilkinson | Dec 16, 2014 | Staff Retention

The Lie Detector Test.

Answer 9: Tom is the thief!

Here is the question again: “During lunch, 5 of Mr. Bryant’s students visit the supermarket. One of the 5, stole an apple.

When questioned…

Jim said: it was Hank or Tom. Hank said: neither Eddie or I did it. Tom Said: you’re both lying. Don said: no one of them is lying, the other is speaking the truth.
Eddie said: no Don, that’s not true.

When the shop owner asked Mr. Bryant, he said that three of the boys are always truthful, but two lie all the time.

So – who stole the apple?”

Let’s work it out.

  • Don and Eddie contradict each other which means one of them must be a liar.
  • One of the remaining boys must also be lying (there are 2 liars).
  • Tom has said ‘you’re both lying’ about the two other remaining boys (Jim and Hank), but there can only be one liar, so it must be him.
  • Jim and Hank are both telling the truth so it can’t be Eddie or Hank who stole the apple.
  • Tom must have stolen the apple.

(I was suspicious about Jim at first, but if you read carefully, Jim said it was Hank OR Tom – so he’s not actually contradicting Hank’s words).

Jim, Hank and Eddie are telling the truth. Don and Tom are the liars.

- Mark Wilkinson
Mark Wilkinson

Mark Wilkinson

Mark is one of the founders of Coburg Banks and heads up the permanent recruitment division of the business.  Every day he helps companies with their recruitment projects, sourcing the very best individuals for their vacancies.  He understands recruitment inside-out.

> More blog posts by Mark Wilkinson

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