Professional and DIY IQ tests are popular because they offer a formula that allows you to compare yourself to other people and see how average (or above average) your intelligence is.

The Cognitive Reflection Test (CRT) is dubbed the world’s shortest IQ test because it only consists of three questions. It assesses your ability to identify that a simple problem may in fact be more difficult than it appears. The faster you do this, the smarter you seem.

## Here are the three questions:

1. A bat and ball cost £1.10 in total. The bat costs £1.00 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?

## Here’s what a lot of people think:

1. 10 pence

2. 100minutes

3. 24 days

When you’re ready, scroll down to find the right answers and how to get there:

1. The ball would actually cost 0.05 pence

If the ball costs X and the bat costs £1 more, then it will be:

X+£1

So

Bat+ball=X + (X+1) =1.1

Thereby

2X+1=1.1 and 2X=0.1

X= 0.05

2. It would take 5 minutes to create 100 widgets.

Five machines can make five widgets in five minutes; therefore, a machine will also make a widget in five minutes.

So if we have 100 machines all making widgets, they can make 100 widgets in five minutes.

3. It would take 47 days for the patch to cover half the lake

If the patch doubles in size every day, it will shrink back in half. So on day 47 the lake is half full.

In a survey of nearly 3,500 people, 33% got all three wrong, and 83% missed at least one.

While this IQ test had its flaws — its brevity and lack of variation in verbal and nonverbal reasoning — only 48% of sampled MIT students were able to answer all three correctly.

How right were you? Tell us below

Give your opinion on our topical democracy. Click the upvote icon at the top of the page to help push this article up the indy100 rankings.

Share.