Bat and Ball Problem

Bat and Ball Puzzle
How Much Does The Ball Cost?

I am busy reading a book called ‘Risk’ by Dan Gardner. In the book ‘Risk’ there is a riddle. It is the bat and ball question. Author, Dan Gardner, says that we have two ways of working problems out and what we will eventually say.

System One and System Two are, apparently, what we use to solve puzzles. The bat and ball riddle tests these two psychological systems. I have solved the question of “how much does the ball cost?”.

Can you work it out for yourself before seeing the answer below 🙂

“Bat & Ball” Cognitive Reflection Test

A bat and ball cost $1.10
If the bat costs $1 more than the ball then what does the ball cost?

The most common and reactive answer is probably what you just said aloud or in your mind.

Yes, the most common answer for that for what the ball costs is 10 cents.

However, you are wrong if you answered 10cents.

How can it be you may ask? Well this is type of a IQ test remember. You will find the answer to the bat and ball quiz at the end of this post.

In the meantime quickly scroll down to the bottom and let me know what you think the answer is and why in the comment section below.

The Correct Answer

The bat and ball quiz is intelligence test that was devised by Shane Fredrick from MIT. It is a test of what type of thinking process you predominately use. Either quickly with little conscious deliberation or slower and more reflective.

Here is how Shane explains why he created the riddle:

Remember that adage about trusting your first instinct? Forget it, says MIT Sloan Professor Shane Frederick, who has developed a simple, three-item test that measures people’s ability to resist their first instinct.

“Do you want someone running your company who doesn’t think beyond their first impulse,” asks Frederick, “or do you want someone who is willing to ask herself, ‘Does this response really make any sense?’” He says that the cognitive reflection test serves as a rough measure of that ability or disposition.

MIT Sloan professor, Shane Frederick, develops new intelligence test article:

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So basically if you answered 10 cents as the price of the ball you rely on your first impulse, system one, as your guidance. But, if you answered correctly then it would have been using reflective objective thinking, system two.

I admit that I first answered 10 cents, but when told it was wrong I then took some time and worked it out.

So the ball costs 5 cents. Can you see why?

The bat was a dollar more than the ball.
This means they both started at the same cost or $1.10 – $1 = 10c
10/2 = 5c
10 is dived by two because there are two items the bat and ball.

So what kind of problem solver are you? Do you use System One (impulse) or System Two (reflective, objective). Feels good to finally have solved the Bat and Ball problem of how much does the ball cost.