This bat and ball riddle reminded me of the riddle about the flu.
You read it and are a little confused.
But if you start with what you know, and take it step by step, it’s perfectly doable.
Question
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?
Answer
We have two equations with two unknowns:
Bat + Ball = $1.10
Ball + $1.00 = Bat
Therefore:
(Ball + $1.00) + Ball = $1.10
Now solve the equation for Ball:
(Ball + $1.00) + Ball = $1.10
Ball + Ball = $.10
2Ball = $.10
Ball = $.05
The ball cost $.05.
The bat cost $1.05.
The bat and ball cost $ 1.10 in total.
I discovered this question via Maria Konnikova’s book Mastermind (Amazon).