A three-question brain teaser, dubbed the world's shortest IQ test, has baffled 83% of participants.
Called the Cognitive Reflection Test, the quiz is part of a research paper published in 2005 by MIT professor Shane Frederick.
But it has since resurfaced online with people keen to test out their IQ after Prof Frederick put it to over 3,000 participants over 10 years ago.
Participants from a range of educational backgrounds, including top American universities such as Yale and Harvard, struggled to work out all the answers.
Of all those who took part only 17% managed to score three out of three on the test, meaning 83% of people failed, The Mirror Online reports.
Speaking about the test, Prof Frederick, said: "The three items on the CRT are 'easy' in the sense that their solution is easily understood when explained, yet reaching the correct answer often requires the suppression of an erroneous answer that springs 'impulsively' to mind."
Here's a look at the questions:
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 is 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?
These are the three most common answers that people guess - but they are actually incorrect.
1. 10 cents
2. 100 minutes
3. 24 days
Professor Frederick adds: "Anyone who reflects upon it for even a moment would recognise that the difference between $1 and 10 cents is only 90 cents, not $1 as the problem stipulates.
"In this case, catching that error is tantamount to solving the problem, since nearly everyone who does not respond '10 cents' does, in fact give the correct response."
Scroll below this picture of the Chasers for the real answers:
The correct answers are:
1. 5 cents
2. 5 minutes
3. 47 days
