We have a similar collection of tests used by one of the societies I was involved with in college, at <a href="http://www.redbrick.dcu.ie/help/exams/" rel="nofollow">http://www.redbrick.dcu.ie/help/exams/</a>
I found this one amusing:<p><pre><code> Rick knows that Jane never lies.
Jane knows that Mike never lies.
Mike knows that Sara never lies.
Jane tells Rick that Mike told her that Sara told him that her dog died.
Should Rick believe the news?
</code></pre>
One could view this in a number of different ways. Jane's statement looks like this: Sara -> Mike -> Jane -> Rick. Interpreting the "truth-telling" as a kind of chain of trust, it too looks like Sara -> Mike -> Jane -> Rick - so Rick should believe the news, right?<p>But Rick doesn't know that Mike tells the truth, so even if Jane tells Rick something Mike said, that in itself may be true, but that doesn't mean that Rick knows that Mike tells the truth.<p>But maybe Jane also told Rick that she knows Mike never lies, so it's OK; the same conversation could have happened all along the chain... but that's assuming something not stated...
Somewhat surreal in places, e.g. the last part of #14:<p><pre><code> How is a hacked computer different from one that hasn't been hacked?
What is a name?</code></pre>