This year’s seasonal flu is the zombie virus. But how far across the population will it spread?

Can you solve it? How many will the zombie outbreak infect?

Greetings, guzzlers.

As it’s Halloween this week...

The world has been overrun by zombies. None has come to Britain – yet.

The infectiousness of this year’s zombie virus, however, is well-known: an infected zombie has a 1/3 chance of passing the infection to a single human, a 1/3 chance of passing the infection to two humans, and a 1/3 chance of passing the infection to no one.

Can you solve it? Are you smarter than a maths jammer? Read more

A single infected zombie arrives on the coast of Britain.

What are the chances that the zombie outbreak will die out after two or fewer humans have become infected? What are the chances that the outbreak will die out by itself? How many people does a typical zombie infect on average? What’s spooky about the answers to the previous questions?

Clarifications: Once a human is infected he or she becomes a zombie. We can assume that Britain has is an unlimited supply of susceptible humans.

I’ll post the solutions on this blog later today. UPDATE: The solution post is now up.

Adam Kucharski became infected by a zombie whilst devising this puzzle. Photograph: Fiona Docherty/Adam Kucharski

Thanks to Adam Kucharski of the London School of Hygiene and Tropical Medicine for coming up with this question. Adam is a world expert on the spread of infectious diseases, like Ebola. He is also the author of the forthcoming book The Perfect Bet, out Spring next year.

I post a puzzle here on a Monday every two weeks. If you like this sort of thing check out my other Guardian blog Adventures in Numberland. You can also check me out on Twitter, Facebook, Google+ and my personal website.

If you like colouring for relaxation you might enjoy my latest book, Snowflake Seashell Star: Colouring Adventures in Numberland, which is out now.

And if know of any great puzzles that you would like me to set here, get in touch.



