Blame It On Your Brain!

Question 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?

Stop reading and answer the question…

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You think the ball costs 10 cents, right?

Congratulations. You are wonderfully wrong!

If the ball costs 10 cents, then that would make the bat, being a dollar more, $1.10. Then the total would be $1.20 when the question clearly said the bat and ball cost $1.10 in total.

Relax, more than 80% of the top students of top universities across the world get this question wrong. You are not one in a million. You are one of the millions who get it wrong!

Why did you brain automatically assume the ball costs 10 cents? Why didn’t it do some simple math that would have made it clear the answer is wrong?

Blame it on your brain. More precisely the way it is wired. The brain loves to conserve mental energy. So, it makes assumptions that reduce the cognitive effort required to form a conclusion or find an answer. Thus, it took the easy way out and presumed the ball to cost 10 cents.

Human mind can perform incredible feats. It can cure cancer. It can put a man on the moon. It can design a supercomputer. But it also has limited cognitive resources.

Tons of research across the world across scientific disciplines – neuroscience to cognitive psychology - have proven the brain can only process a small amount of information at any given time. Once the brain’s threshold is surpassed, its capacity to cognitively grasp information is severely diminished.

You and me often substitute difficult problems with simpler ones so we could solve them quickly. This intuitive process leads people astray.

Daniel Kahneman and Amos Tversky, who posed the ball-bat question, in their fascinating book Thinking Fast And Slow sums up out speedy stupidity this way:

‘When asked questions a plausible answer comes to mind immediately. Overriding it requires hard work. The insistent idea that ‘it’s true’ makes it difficult to check the logic and most people do not take the trouble to think through the problem.’

Now you know how we answer life’s problems so fast. And so wrong!

And if you think you are smart now and won’t make the same mistake again, here are three more questions.

Question 2: If it takes 5 machines to make 5 toys, how long would it take 100 machines to make 100 toys?

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If you answered 100, I am sorry. The answer is 5 minutes. Figure it out yourself!

Relax a little and at least get the next two questions right.

Question 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 to cover half of the lake?

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If you answered 24, my deepest condolences. The answer is 47 days!

Do you seriously want to try the last question? Well, it’s your funeral. See if you get at least this one right.

Question 4: When I was 4, my sister was half my age. Today, I am 100. How old is my sister?

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If you said 50, your intuition needs a complete overhaul.

If your sister was half your age when you were 4, she was 2 years old meaning that she is 2 years younger than you. So, if you are 100, she should be 98.

If you think you now know how the human mind works, wait till you learn about System 1 and System 2 thinking. For that, you have to read the book Thinking Fast and Slow!