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The 'world's shortest' IQ test only has three questions and a 17 per cent pass rate.
The 'world's shortest' IQ test consists of just three questions, with only 17 per cent of participants able to pass the trio of brain teasers. Known as the Cognitive Reflection Test, the test was originally part of a research paper published in 2005 by Massachusetts Institute of Technology (MIT) professor Shane Frederick.
In a study, Professor Frederick made more than 3,000 participants from a range of educational backgrounds complete the IQ test. Out of all who completed the test, only 17 per cent managed to score three out of three.
"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." Professor Frederick said.
The paper has since gone viral after resurfacing as thousands of people see if they can pass the test - see if you can answer the questions correctly below.
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?
I'll leave it a while before I post the correct answers along with the most common wrong answers.
In a study, Professor Frederick made more than 3,000 participants from a range of educational backgrounds complete the IQ test. Out of all who completed the test, only 17 per cent managed to score three out of three.
"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." Professor Frederick said.
The paper has since gone viral after resurfacing as thousands of people see if they can pass the test - see if you can answer the questions correctly below.
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?
I'll leave it a while before I post the correct answers along with the most common wrong answers.
Comments
1. 5 cents
2. 5 minutes
3. 47 days?
Ball cost
0.05p100 machines
5 minutes ?Lily pads
47 days?a+b = 1.10 and a-b = 1.00 therefore 2a = 2.10 (adding the previous two equations together, eliminates b)
Therefore if 2a = 2.20 a = 1.05, therefore if a = 1.05 and a+b = 1.10, b = 0.05
Made much harder by the question leading you to think the bat is $1 and the ball is 10 cents, BUT the difference between them then is only 90 cents.
Below you will find the three most common answers which are in fact all 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."
What are the correct answers?
Read below to find the correct answers for each question:
1. 5 cents
2. 5 minutes
3. 47 days
If you're still a bit confused by the answers even after reading them, an explanation for their equations has been provided by Presh Talwalkar, the author of The Hoy of Game Theory: AN Introduction to Strategic Thinking. He has provided the following explanations for each solution:
1. Say 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 machines 5 minutes to make 5 widgets, then it takes 1 machine 5 minutes to make 1 widget (each machine is making a widget in 5 minutes). If we have 100 machines working together, then each can make a widget in 5 minutes. So there will be 100 widgets in 5 minutes.
3. Every day FORWARD the patch doubles in size. So every day BACKWARDS means the patch halves in size. So on day 47 the lake is half full.