Harvard cognitive psychologist Steven Pinker has a new book, Rationality, in which he makes the case that our gut instincts are often, if not always, wrong.
He used, as an example, what he calls a “simple logic” question:
A smartphone and case, combined, cost £110. The phone costs £100 more than the case. How much is the case?
What is your answer?
Scroll down for the correct answer.
If you answered £10, like most people you are wrong.
The correct answer is £5.
Here’s how I figured it out:
If X is smart phone, and Y is the case.
X+Y = £110
X = £100+Y
£110 = £100+2Y
Therefore Y = £5 and X = £100+£5 = £105