Test your knowledge on the world’s shortest IQ test that 83% of people fail


If you like quizzes, we have the one that suits you best.

It’s the world’s shortest IQ test, consisting of just three questions – but less than one in five pass. While there are many time-consuming ways to test your intelligence, one of the most common is to take an IQ test.

Some have lots of questions to really test your brain strength. Because this one only has three and even though it sounds simple enough, only about 17% of people succeed with it.

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It’s the shortest test out there and may seem like child’s play, but don’t let it surprise you. It’s called the Cognitive Reflection Test (CRT) and was published in a research paper in 2005 by Professor Shane Frederick, reports The Mirror.

Speaking of the test, Professor Frederick said: “The three elements of the CRT are ‘easy’ in the sense that their solution is easily understood when explained, but arriving at the correct answer often requires deleting a wrong answer. that ‘impulsively’ pops up in the mind.”

It has since resurfaced online and many have tried it. In total, 83% failed: can you pass?


1. A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the balloon 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 is a patch of water lilies. Every day, the patch doubles in volume. If it takes 48 days for the plot to cover the entire lake, how long would it take for the plot to cover half of the lake?

The most common answers given – which are wrong:

1. 10 cents

2. 100minutes

3. 24 days

Professor Frederick adds: “Anyone who thinks about it for even a moment would recognize that the difference between $1 and 10 cents is only 90 cents, not $1 as the problem states.

“In this case, catching that error is like solving the problem, since almost everyone who doesn’t answer ’10 cents’ actually gives the correct answer.”

The correct answers are:

1. 5 cents

25 minutes

3. 47 days

Confused? Presh Talwalkar, the author of The Hoy of Game Theory: An Introduction to Strategic Thinking, explained how to find the right answers on his blog, Mind Your Decisions.

1. Suppose the ball costs X. Then the bat costs $1 more, so it is X + 1. So we have bat + ball = X + (X + 1) = 1.1 because together they cost $1.10. This means 2X + 1 = 1.1, then 2X = 0.1, so X = 0.05. This means the ball costs 5 cents and the bat costs $1.05

2. If it takes 5 minutes for 5 machines to create 5 widgets, it takes 5 minutes for 1 machine to create 1 widget (each machine makes a widget in 5 minutes). If we have 100 machines working together, each can create a widget in 5 minutes. So there will be 100 widgets in 5 minutes.

3. Each day, the FORWARD patch doubles in size. So every day BACKWARDS means the patch halves. Thus, on day 47, the lake is half full.



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