Skip to main content

Challenge 172: Flipping Fortune

How likely am I to save 20p or less?

I have a collection of five coins: one 1p, one 2p, one 10p, one 20p and one 50p.

They are all fair coins, equally likely to show heads or tails.

I toss all the coins simultaneously and put any that come up tails in my savings jar.

What is the probability that I save 20p or less?

(You should assume that no coins land on their edge!)