Brain teaser

<h2 id="example">Example</h2>
Q: <i>If three hens lay three eggs in three days, how many eggs does a (statistical) hen lay in one day?</i>
A1: <i>One third.</i> (Note: 3 hens = 3 eggs / 3 days → 3 hens = (3 / 3) (eggs / days) → 1 hen = (1 / 3) (egg / days))
A2: <i>Zero or one</i> (it's hard to lay a third of an egg).
<p>One can argue about the answers of many brain teasers; in the given example with hens, one might claim that all the eggs in the question were laid in the first day, so the answer would be three.
</p>
Q: <i>Mary's father has five daughters: 1. Nana, 2. Nene, 3. Nini, 4. Nono. What is the name of the fifth daughter?</i>
A: <i>Mary</i>. The first four daughters all have names with the first 4 vowels, so if someone does not think about the question, they may say the name with the fifth vowel, Nunu. The answer was given at the beginning of the question (i.e., Mary's father has five...)
Q: <i>What appears once in a minute, twice in a moment, but never in a thousand years?</i>
A: The letter "M".
Q: <i>I am the beginning of the end, the beginning of eternity, and the end of all time?</i>
A: The letter "E".
<h2 id="intuition">Intuition</h2>
<p>The difficulty of many brain teasers relies on a certain degree of fallacy in human <a href="/facts/Intuition_(knowledge)/Mshu0Vxb">intuitiveness</a>. This is most common<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> in brain teasers relating to <a href="/facts/Conditional_probability/QcN2UERV">conditional probability</a>, because the causal <a href="/facts/Mind/Y5JhtFj4">human mind</a> tends to consider absolute probability instead. As a result, controversial discussions emerge from such <a href="/facts/Problem_solving/9cuLz5pH">problems</a>. One of the famous brain teasers is the <a href="/facts/Monty_Hall_problem/w1X1bUrf">Monty Hall problem</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> Another (simpler) example of such a brain teaser is the <a href="/facts/Boy_or_Girl_paradox/0lNlkYrM">Boy or Girl paradox</a>.
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Board_games/ctkuzWJU">Board games</a></li>
<li><a href="/facts/Mathematical_game/96L20FzX">Mathematical game</a></li>
<li><a href="/facts/Mensa_International/tq3KssrP">Mensa</a></li>
<li><a href="/facts/Mind_sport/4q5ECcGE">Mind sport</a></li>
<li><a href="/facts/Boy_or_Girl_paradox/0lNlkYrM">Boy or Girl paradox</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Editors of Time-Life books, Inc. (1989). The Puzzle Master. Alexandria, Virginia, USA: Time-Life Books. p. 18. ISBN 0-8097-0928-7. {{cite book}}: |author= has generic name (help) <a href="0-8097-0928-7" target="_blank">0-8097-0928-7</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Bar-Hillel, Maya; Noah, Tom; Frederick, Shane (2018). "Learning psychology from riddles: The case of stumpers". Judgment and Decision Making. 13: 112–122. doi:10.1017/S193029750000886X. Retrieved 2021-07-09. <a href="http://journal.sjdm.org/17/171117/jdm171117.html" target="_blank">http://journal.sjdm.org/17/171117/jdm171117.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>"Game Show Problem | Marilyn vos Savant". Archived from the original on 2013-01-21. Retrieved 2021-07-09. <a href="https://web.archive.org/web/20130121183432/http://marilynvossavant.com/game-show-problem/" target="_blank">https://web.archive.org/web/20130121183432/http://marilynvossavant.com/game-show-problem/</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
</ol>

Brain teaser open-in-new

Brain teaser