![Placeholder: several colourful numbers](/themes/nrich/images/nrich_small_placeholder.png)
Conditional probability
![Placeholder: several colourful numbers](/themes/nrich/images/nrich_small_placeholder.png)
![Do you brush your teeth every day?](/sites/default/files/styles/medium/public/thumbnails/content-id-13897-icon.png?itok=0kwSNxd4)
problem
Do you brush your teeth every day?
How can we find out answers to questions like this if people often lie?
![Drug testing](/sites/default/files/styles/medium/public/thumbnails/content-id-7328-icon.png?itok=qjwu6HVX)
problem
Drug testing
How do different drug-testing regimes affect the risks and payoffs for an athlete who chooses to take drugs?
![Non-Transitive Dice](/sites/default/files/styles/medium/public/thumbnails/content-id-7541-icon.jpg?itok=fJByZDgA)
problem
Non-Transitive Dice
Alison and Charlie are playing a game. Charlie wants to go first so Alison lets him. Was that such a good idea?
![Ante Up](/sites/default/files/styles/medium/public/thumbnails/content-id-7295-icon.png?itok=iwmHCoxK)
![At least one...](/sites/default/files/styles/medium/public/thumbnails/content-id-7286-icon.png?itok=J083AvXf)
problem
At least one...
Imagine flipping a coin a number of times. Can you work out the probability you will get a head on at least one of the flips?
![Mathsland National Lottery](/sites/default/files/styles/medium/public/thumbnails/content-id-7238-icon.png?itok=YHeN5V9q)
problem
Mathsland National Lottery
Can you work out the probability of winning the Mathsland National Lottery?
![Same Number!](/sites/default/files/styles/medium/public/thumbnails/content-id-7221-icon.png?itok=qzwUKYL2)
problem
Same Number!
If everyone in your class picked a number from 1 to 225, do you think any two people would pick the same number?
![Dicey Dice](/sites/default/files/styles/medium/public/thumbnails/content-id-6953-icon.png?itok=VLFjdybu)
![X-Dice](/sites/default/files/styles/medium/public/thumbnails/content-id-6611-icon.jpg?itok=CtOgbqPt)
problem
X-Dice
Explore these X-dice with numbers other than 1 to 6 on their faces.
Which one is best?