The Quiz - The Harvard Tease
Harvard students are smart, smart kids.
A bat and ball cost $1.10.
Keep scrolling for the answer...
The correct answer is
You might have answered 10¢.
That’s what more than 50% of Harvard students answered. But the real answer is 5¢.
Behavioural economist Daniel Kahneman explains why most people get this wrong:
A number came to your mind. The number, of course, is 10: 10¢. The distinctive mark of this easy puzzle is that it evokes an answer that is intuitive, appealing, and wrong. Do the maths, and you will see. If the ball costs 10¢, then the total cost will be $1.20 (10¢ for the ball and $1.10 for the bat), not $1.10.
The correct answer is 5¢.
It is safe to assume that the intuitive answer also came to the mind of those who ended up with the correct number—they somehow managed to resist the intuition.
Many thousands of university students have answered the bat-and-ball puzzle, and the results are shocking.
More than 50% of students at Harvard, MIT, and Princeton gave the intuitive—incorrect—answer.
At less selective universities, the rate of demonstrable failure to check was in excess of 80%. The bat-and-ball problem is our first encounter with an observation that many people are overconfident, prone to place too much faith in their intuitions. They apparently find cognitive effort at least mildly unpleasant and avoid it as much as possible.