The cognitive thinking test only has three questions, but many people struggle to pass it, including Yale and Harvard students.

The common IQ test is a great way to test your knowledge, but most are quite long and consist of many questions.

But if you want to give your brain a quick workout, there’s a much quicker test you can take to determine your IQ.

The cognitive reflection test is considered the shortest IQ test in the world and consists of only three questions.

Although short, the seemingly simple test has left many perplexed, with only 17% able to pass it in one study.

**What is the Cognitive Thinking IQ Test?**

The Cognitive Thinking Test was originally part of a research paper published in 2005 by Professor Shane Frederick of MIT, and has recently resurfaced online with many people trying it.

As part of his research, Professor Frederick asked more than 3,000 participants from various educational backgrounds to take the test, but even those who attended top US universities such as Yale and Harvard struggled to find all the answers. .

Professor Frederick said: “The three elements of CRT are ‘easy’ in the sense that their solution is easily understood when explained, but arriving at the correct answer often requires removing a wrong answer that comes ‘impulsively’ “in mind.”

**What are the questions?**

1. A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the balloon 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 water lilies. Every day, the patch doubles in volume. If it takes 48 days for the plot to cover the entire lake, how long would it take for the plot to cover half of the lake?

**What are the answers?**

These are the three most common answers that people guess, but are actually incorrect:

Professor Frederick said: “Anyone who thinks about it for even a moment would recognize that the difference between $1 and 10 cents is only 90 cents, not $1 as the problem states.

“In this case, catching this error is like solving the problem, since almost everyone who doesn’t answer ’10 cents’ actually gives the correct answer.”

**Perplexed? Here are the answers explained**

Presh Talwalkar, the author of The Hoy of Game Theory: An Introduction to Strategic Thinking, explained how to find the right answers for each of the three questions on his blog, Mind Your Decisions.

1. Suppose 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 five cents and the bat costs $1.05

2. If it takes five machines five minutes to create five widgets, it takes one machine five minutes to create a widget (each machine makes a widget in five minutes). If we have 100 machines working together, each can create a widget in five minutes. So there will be 100 widgets in five minutes.

3. Each day, the FORWARD patch doubles in size. So every day BACKWARDS means the patch halves. Thus, on day 47, the lake is half full.