# Only 17% of people can pass ‘world’s shortest’ three-question IQ test

The Cognitive Reflection Test is thought to be the shortest IQ test in the world, comprising only three questions.

However, many people still find it difficult with only around 17% of people able to pass it during a study.

The common IQ test is a great way to test your knowledge. But most are pretty lengthy.

This IQ test would seem simple with only three questions - but left 83% of people boggled and failing the test.

## What is the Cognitive Reflection IQ test?

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

As part of his research, Professor Frederick had more than 3,000 participants from a range of educational backgrounds complete the test, but even those attending top American universities such as Yale and Harvard struggled to work out all the answers.

Professor Frederick said: "The three items on the CRT are ‘easy’ in the sense that their solution is easily understood when explained, yet reaching the correct answer often requires the suppression of an erroneous answer that springs ‘impulsively’ to 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 ball 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 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?

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

1. 10 cents2. 100 minutes3. 24 days

Professor Frederick said: "Anyone who reflects upon it for even a moment would recognise that the difference between \$1 and 10 cents is only 90 cents, not \$1 as the problem stipulates.

"In this case, catching that error is tantamount to solving the problem, since nearly everyone who does not respond ‘10 cents’ does, in fact, give the correct response."

The correct answers are:1. Five cents2. Five minutes3. 47 days