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28th Mar 2024

‘World’s shortest IQ test’ will tell you if you’re smarter than 80% of humanity

Charlie Herbert

World's shortest iq test

Just three question to establish whether you’re the wheat or the chaff

Most tests to establish your intelligence are long and let’s be honest quite boring. So, here’s the solution if you can’t be bothered to sit through 50 questions asking you to find the pattern in a sequence.

Psychologist Shane Frederick got 3,428 students from some of America’s top universities to take part in what has been dubbed the ‘world’s shortest IQ test.’

The Cognitive Reflection Test is made up of just three questions, and from 2003, Frederick got respondents to complete the test in 35 separate studies over a 26-month period.

Only 17 percent of those who took part were able to answer all three questions correctly, with 33 percent getting all three wrong.

The questions are:

  1. A bat and a ball cost $1.10 in total, the bat costs $1 more than the ball. How much does the ball cost?
  2. If it takes five machines five minutes to make five widgets, how long would it take 100 machines to make 100 widgets?
  3. In a lake there’s a patch of lily pads. Every day the patch doubles in size, if it takes 48 days for the patch to cover the entire lake how long would it take for the patch to cover half of the lake?

Frederick explained in a paper for the Journal of Economic Perspective that these questions were selected because they “yield impulsive erroneous responses.”

Basically, this means the answer that comes into your head when you first read the question is usually the wrong one.

So, the all important answers. We’ll warn you, if you said 10 cents, 100 minutes and 24 days, you may want to go back and rethink your answers.

The correct answers are: Five cents, five minutes and 47 days.

If those answers make no sense to you, you can find the explanations here.

And if you’re reading this thinking “Yeah obviously they were the answers, piece of cake” then congratulations, you can feel very smug about being more intelligent than most.

Related links:

Girl, 11, with autism, has higher IQ than Albert Einstein and Stephen Hawking

Are you clever enough to solve these three fiendishly difficult brain teasers?