Known as the shortest IQ test, the Cognitive Reflection Test (CRT) consists of only three questions. But for most it is difficult, as only 17% of the study participants were able to pass it.

IQ tests are a recognized method of assessing ability. But most are quite long. The CRT looks simple, with only three questions, but he failed 83 out of 100.

What is a CRT?

The cognitive reflection test was part of a 2005 research paper by Shane Frederick, a professor at the Massachusetts Institute of Technology, and has recently gained popularity again.

In the study, Professor Frederick tested 3,000 participants with different levels of education, but even some of the leading universities, such as Yale and Harvard, were confused when they gave the answers.

Frederick explained, “The three topics in CRT are simple in the sense that the solutions are easy to understand if they are explained. But the right decisions require holding back the wrong answers from the impulse of the moment.”

Here is the question

1. Baseball: a bat and a ball cost $1.10. The bat costs a dollar more than the ball. How much is the ball?

2. If five machines produce five parts in five minutes, how long will it take 100 machines to produce 100 parts?

3. There are a lot of water lilies in the lake. Every day the lump doubles its area. If the lump took 48 days to cover the entire lake, how long did it take to cover half of the lake?

answers

There are three most common answers, but in reality they are all wrong. Here they are:

1.10 cents

2100 minutes

3.24 days

Professor Frederick said: “Anyone who thinks a little bit realizes that the difference between a dollar and 10 cents is 90 cents, not a dollar, as the problem requires. In this case, almost everyone who misses 10 cents is actually giving the correct answer.”

Correct answers:

1. Five cents

2. Five minutes

3.47 days

Here is the explanation

Presh Talwalkar, author of The Hoy of Game Theory. Introduction to strategic thinking”, explained:

1. Suppose the ball costs “X” cents. If the club is worth a dollar more, it’s X+1. So, ball + bat = X+X+1, and together they add up to $1.10. So 2X+1=1.10, so 2X=0.1, so X=0.5. This means that the ball costs 5 cents and the bat costs $1.05.

2. If five machines produce five parts in five minutes, this means that each machine produces one part in five minutes (since each machine only produces one part). If we have 100 machines working together, each of them will produce a part also in five minutes. So in five minutes we will have 100 pieces.

3. Every day, the lump doubles its area. Therefore, on each previous day, he had half the area. Thus, on the 47th day, the lake will be covered by half of its surface.

Source: Bournemouth Daily Echo