The “World’s Shortest IQ Test” Has Only 3 Questions – But Can You Get Them Right?

Want to test your intellectual capacity without spending two hours (and probably a bunch of money) on a full-blown IQ test? Then the Cognitive Reflection Test (CRT) might just be the one for you – but fair warning, it’s harder to get a perfect score than you might think.

The CRT was created by Yale University Professor Shane Frederick in 2005 (though he was working at MIT back at that time) and consists of three math-based questions aimed at assessing your gut responses versus your more rational thought processes.

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 5 machines 5 minutes to make 5 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?

At first glance, these questions might seem incredibly simple, but there’s something important to remember. Frederick designed them specifically to see how good you are at ignoring your intuition – in other words, the first answer that you think of – and instead taking a more careful, analytical approach.

While how many of the questions you can answer correctly is the main measure of the CRT, it might also give you something else to show off about if you score well and get to the correct answer quickly.

The answers

1. 5 cents – Did you say 10 cents? That’s what Frederick was expecting your gut instinct to be, but a 5-cent ball plus a $1.05 bat does indeed make the magical $1.10. According to Frederick’s study investigating the CRT, out of the 3428 people who carried out the test, those who answered 10 cents were found to be “significantly less patient” than those who answered correctly.

2. 5 minutes – The intuitive response would be to carry on the pattern,100 minutes for 100 machines to make 100 widgets. On closer inspection, each individual machine takes 5 minutes; scale that up to 100 machines and each one still only takes 5 minutes.

3. 47 days – The most likely wrong answer here is 24 days, with the instinct being to halve the number of days because you’re halving the size of the area covered by the lily pads. However, if the patch doubles in size each day, that means that it was half the size only one day before 48 days, thus the answer is 47 days. 

How many of the questions did you get correct? Don’t worry if you didn’t score very high – there’s plenty of reason to ignore intelligence tests anyway. Learn more in the video below.

If you’re still looking for consolation, you might be reassured that only 20 percent of those tested at Harvard University, 26 percent at Princeton University, and 48 percent at MIT – some of the most prestigious academic institutions in the world – got all three answers correct.