'World's shortest IQ test' only has 3 questions—can you breeze through them?

[Marshy]

 

Do you often question your intelligence? If you have just a couple of minutes to spare, try the short and sweet Cognitive Reflection Test (CRT), much regarded as the “world’s shortest IQ test” as it only has three (deceptively simple) questions. Developed in 2005 by Shane Frederick, an economics professor at Yale University, these mind-benders are less about raw intelligence and more about the ability to pause, reflect, and engage in deeper thinking.

 

Want to give it a shot? Here are the questions:

 

 

Think you’re a quick thinker? Unfortunately, that might not be to your advantage. Taking the CRT is a battle between two sides of your mind: the impulsive, snap-judgment-making part, and the slower, more thoughtful one. You would need to silence the first and listen to the second.

 

 

Ready for the solutions? Scroll on for the answers.

 

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If you answered 5 cents, 5 minutes, and 47 days respectively, you’ve aced the test and resisted impulsive answers to dive into more deliberate thought processes.

 

Let’s start with the bat and ball problem. The solution hinges on careful consideration of the given information. We know the total cost is $1.10, and the bat costs $1 more than the ball. If we let x represent the cost of the ball, we can express the bat’s cost as x + $1. The equation becomes x + (x + $1) = $1.10. Solving this, we find x = $0.05. So, the ball costs 5 cents, and the bat costs $1.05. The trap here is the temptation to quickly assume the ball costs 10 cents, which doesn’t satisfy the “$1 more” condition.

 

Moving on to the widget conundrum, the key is to focus on the rate of production rather than the total number of machines or widgets. In the original scenario, we see that one machine produces one widget in 5 minutes. This rate doesn’t change when we scale up to 100 machines. Each machine will still take 5 minutes to produce one widget, so 100 machines will produce 100 widgets in the same 5-minute period. The trick is to avoid the impulse to multiply the time by the increase in machines.

 

Finally, we have the lily pad puzzle. This one requires us to think backwards. If the lake is fully covered on day 48, and the patch doubles each day, then on day 47, half the lake must have been covered. The trap here is to divide 48 by 2, which ignores the exponential growth of the lily pads. Remember, each day the patch doubles, so the day before full coverage, it must be half-covered.

 

Frederick’s research, published in the Journal of Economic Perspectives, revealed that even at prestigious institutions like Harvard and Yale, only 17% of respondents aced all three questions, whereas 63% got one or none correct.

 

The CRT has been linked to the concept of ‘System 1’ and ‘System 2’ thinking, popularized by psychologist Daniel Kahneman in the book Thinking, Fast and Slow. System 1 is your quick, gut-reaction mode, while System 2 is your slower, more analytical approach.

 

So, how did you stack up against this short but tough puzzler? If you found yourself tripping up on the questions, you’re not alone. But the real takeaway is whether you can slow down and think things through—a valuable skill in decision-making beyond just quizzes.

 

• https://mymodernmet.com/shortest-iq-test-in-the-world/ 
• https://www.rd.com/article/worlds-shortest-iq-test/ 
• https://www.good.is/worlds-shortest-iq-test-with-just-3-questions-can-reveal-how-intelligent-you-are 
• https://www.iheart.com/content/2019-07-22-heres-the-worlds-shortest-iq-test-and-only-17-of-people-can-pass-it/ 

 

 

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