The World’s Shortest IQ Test: People Can Find Out How Smart They Are in Just 3 Steps

The World’s Shortest IQ Test: Find Out How Smart You Are in Just 3 Steps

About 83% of people fail at least one of the questions on the “IQ Test.” Do people think they have the right answers for the Cognitive Reflection Test (CRT)? According to Wikipedia, the CRT is the world shortest IQ test. (1)

With only 3 questions, it can separate the Einsteins from the Simpsons of this world.

In 2005, psychologist Shane Frederick was the first to design this IQ test. Its goal is to test your ability to think rationally and slowly. But, most importantly, it tests you to see if you can ignore your gut response.

In other words, it is designed to test how good you are at ignoring your intuition and focusing on your analytic thinking.

In one survey 3,428 people participated. They tried to answer this IQ test. Surprisingly, 33% of them failed to answer these 3 questions. About 83% of them answered at least one question incorrectly. Even well-educated people had the wrong answers.

About 48% of MIT students managed to answer all of these questions correctly. In a study from 2003, only 17% of the participants answered all questions correctly. But, if you can’t answer all of these questions, do not beat yourself up.

How hard can they be? Well, since this test only has 3 questions, people call it the shortest IQ test. But, every single question tests your ability to identify the difficulty of the problem.

In other words, once you read these questions, your brain will automatically register them as hard to solve.

Experts claim that if you answer all of them correctly, you might be a genius. So, think carefully.

The Cognitive Reflection Test Questions

Question #1: A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball. How much does the ball cost?

Question #2: If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets?

Question #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?

Read below to find out the correct answers.


  • The answer to the first question is 5 cents. You probably answered 10 cents. But that is not quite right. When you have a ball that costs 5 cents, and a bat that costs 1.05 cents you get to $1.10. So, it is clear that 1$.05 is $1 more expensive than 5 cents.
    According to a study from the University of Princeton, people who answered “10 cents” were less patient than others who answered correctly.
  • The answer to the second question is 5 minutes. You probably answered 100 minutes, but that is not correct. Since 5 minutes are needed for one machine to produce one widget, a hundred machines would need 5 minutes to produce a hundred widgets.
  • The answer to the last question is 47 days. Did you guess 24 days? Have in mind that the area of the lily pads patch doubles every day. So, the lake needs just a day to go from half covered to fully. When you take a day away from 48, you get 47.

So, did you answer correctly?