Bat and Ball Question

If a bat and a ball together cost £1.10, and the bat costs a pound more than the ball, how much does the ball cost ?

This question is part of the Cognitive Reflection Test, CRT, which was first described in 2005 by psychologist Shane Frederick. The answer for the The bat and ball question was developed by the behavioural economist Shane Frederick of Yale University and made famous by Nobel laureate Daniel Kahneman in his book Thinking, Fast and Slow. It is an elegant illustration of Kahnemans model of the human mind, in that we have two modes of thinking. There is a fast, intuitive processing system, which solves many problems with graceful ease but can also be tempted into error, and there is a slower, more effortful logic module, which can give out the right answer when it must.

(c) Compiled by B V & T M Wood.

All rights reserved.

Disclaimer

The usual quick answer given is 10 pence but this is not correct. If the ball costs 10 pence, then the bat would cost £1.10, which would bring the total to £1.20. ...For the bat to cost one pound more than the ball, the ball must cost 5 pence and the bat £1.05.

This question is part of the Cognitive Reflection Test, CRT, which was first described in 2005 by psychologist Shane Frederick. The answer for the The bat and ball question was developed by the behavioural economist Shane Frederick of Yale University and made famous by Nobel laureate Daniel Kahneman in his book Thinking, Fast and Slow. It is an elegant illustration of Kahnemans model of the human mind, in that we have two modes of thinking. There is a fast, intuitive processing system, which solves many problems with graceful ease but can also be tempted into error, and there is a slower, more effortful logic module, which can give out the right answer when it must.

(c) Compiled by B V & T M Wood.

All rights reserved.

Disclaimer