Puzzle #8: The Cognitive Reflection Test
A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball. How much does the ball cost?
If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets?
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?
These questions are directly quoted from a research paper by Shane Frederick. Do you tend to follow your gut instinct when faced with a new problem? Or are you more likely to take a slow, methodical approach? Everybody uses some mix of these two cognitive modes in their lives, and The Cognitive Reflection Test was designed to measure people’s tendencies toward one or the other. If the answers seemed immediately obvious to you, you may have been relying on your intuitive thinking, when in fact these puzzles require a little more reflection than one might expect. Give them another slower pass and see if any of your answers change.
Find the solutions at the bottom of this page.
