Live Problems - Stage 3 & 4

Each time you visit the NRICH site there will be some activities which are 'live'. That means we are inviting you to send us your solutions and we will publish a selection of them, along with your name and school. If you'd like to read more about what we're looking for, read this short article.

Wild Maths - share what you have tried and discoveredlive

Stage: 3 and 4

Here's how you can send your solutions to these Wild Maths problems. You may be featured in our Showcase!

Gabriel's Problemlive

Stage: 3 and 4 Challenge Level: Challenge Level:1

Gabriel multiplied together some numbers and then erased them. Can you figure out where each number was?

Spots and Measleslive

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

99% of people who have measles have spots. Ben has spots. Do you think he has measles?

Do Rare Events Happen?live

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

I'd be very surprised if I had three children all with the same birthday, but I read in the paper that it happened to one family...

The ELISA Testlive

Stage: 4 and 5 Challenge Level: Challenge Level:2 Challenge Level:2

In 1% of cases, an HIV test gives a positive result for someone who is HIV negative. How likely is it that someone who tests positive has HIV?

Matching Criminalslive

Stage: 4 and 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

DNA profiling is an invaluable tool for the police. However, when it comes to probability, things aren't always as straightforward as they seem.

Stage 3 and 4 Toughnutslive

Stage: 3 Challenge Level: Challenge Level:1

These Stage 3 and 4 problems have not yet been solved. Can you be the first?