The challenge
A bat and a ball together cost $1.10. The bat costs $1.00 more than the ball. How much does the ball cost?
Objective
Reveal the difference between fast intuitive thinking (System 1) and slow deliberate reasoning (System 2).
Materials
Just your mind.
Description
This problem is part of the Cognitive Reflection Test developed by Shane Frederick. It is designed to trigger an intuitive wrong answer that feels correct. Studies show that most people — including those with high IQs — answer $0.10 on first instinct. Slowing down and checking the answer is a skill that can be practiced.
Source: https://en.wikipedia.org/wiki/Cognitive_reflection_test
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