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Solve 3 trick puzzles and find out how smart you are
Solve 3 trick puzzles and find out how smart you are

If big IQ tests scare you, take this quick test.

Solve 3 trick puzzles and find out how smart you are
Solve 3 trick puzzles and find out how smart you are

In 2005, MIT professor Shane Frederick came up with a test to test cognitive abilities. It consists of only three questions, which is why it is often called the shortest IQ questionnaire.

As an experiment, 3,428 respondents with different educational backgrounds passed the Cognitive Reflection and Decision Making test. Only 17% of the participants succeeded in answering all three questions correctly. Check if you can be one of them.


1. A baseball bat and ball cost $ 1 and 10 cents together. A bat is $ 1 more expensive than a ball. How much does the ball cost?

2. It takes five machines in the factory five minutes to make five parts. How many minutes will 100 machines take to produce 100 parts?

3. Water lilies grow on the lake. Their number doubles every day. If water lilies take 48 days to completely cover the entire surface of a lake, how long will it take for them to cover only half?

If you answered 10 cents, 100 minutes and 24 days, we hasten to upset you: these are the wrong decisions. Try to go back to the tasks and think about them again without rushing. If you have given answers other than these, feel free to read on.

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beautiful water lilies from the same problem
beautiful water lilies from the same problem

What's the catch?

The tasks are formulated in such a way that, with their deceptive simplicity, they push towards intuitive solutions. But some people, despite the desire to give an instant, but wrong answer, notice the catch and begin to read the assignments more closely. This ability to resist impulsive responses is called cognitive reflection.

In order to pass this test, it is important to reject the answer that comes to mind first.

Shane Frederick professor, author of these tricky problems

When making decisions, intuitive thinking starts to work first. When he cannot find a suitable answer, it connects. Even if you made mistakes in all three tasks, this does not mean that you are incompetent. It only says that the analytical part of thinking did not have time to get involved in the work. Here are the conclusions that can be drawn from this:

  • People who make mistakes the first time they take a test are more impulsive and spontaneous and don't like to wait.
  • People who answer questions correctly the first time are more rational, more focused, and take the time to make decisions.

1. If the ball were really worth 10 cents, then a bat that is $ 1 more expensive would be worth $ 1 + 10 cents. This contradicts the conditions of the problem. Let's take a look at the solution. Let's say the price of the ball is X. The bat costs $ 1 more - X + 1. We get the following equation: X + (X + 1) = 1, 1, because together the bat and the ball cost 1, 1 dollar. We solve the equation:

2X + 1 = 1, 1;

2X = 1, 1 - 1;

2X = 0, 1;

X = 0.05.

So the ball is worth 5 cents and the bat is $ 1.05.

Answer: 5 cents.

2. If five machines make five parts in five minutes, then one machine makes one part in five minutes. If 100 machines make parts, they will make 100 in the same five minutes.

Answer: five minutes.

3. Water lilies fill the entire pond in 48 days. For the pond to be half full, you only need to go back one day, as the thickets of flowers double in size daily.

Answer: 47 days.

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