Two's Company
Age 11 to 14
Challenge Level
Seven balls are shaken. You win if the two blue balls end up touching. What is the probability of winning?
Cosy Corner
Age 11 to 14
Challenge Level
Six balls are shaken. You win if at least one red ball ends in a corner. What is the probability of winning?
Litov's Mean Value Theorem
Age 11 to 14
Challenge Level
Start with two numbers and generate a sequence where the next number is the mean of the last two numbers...
Which Spinners?
Age 14 to 18
Challenge Level
Can you work out which spinners were used to generate the frequency charts?
Searching for Mean(ing)
Age 11 to 16
Challenge Level
If you have a large supply of 3kg and 8kg weights, how many of each would you need for the average (mean) of the weights to be 6kg?
Last One Standing
Age 14 to 16
Challenge Level
Imagine a room full of people who keep flipping coins until they get a tail. Will anyone get six heads in a row?
Same Number!
Age 14 to 16
Challenge Level
If everyone in your class picked a number from 1 to 225, do you think any two people would pick the same number?
Mathsland National Lottery
Age 14 to 16
Challenge Level
Can you work out the probability of winning the Mathsland National Lottery?
Who's the Best?
Age 11 to 14
Challenge Level
Which countries have the most naturally athletic populations?
Non-transitive Dice
Age 11 to 14
Challenge Level
Alison and Charlie are playing a game. Charlie wants to go first so Alison lets him. Was that such a good idea?
Odds and Evens Made Fair
Age 14 to 16
Challenge Level
In this follow-up to the problem Odds and Evens, we invite you to analyse a probability situation in order to find the general solution for a fair game.
Estimating Time
Age 11 to 14
Challenge Level
How well can you estimate 10 seconds? Investigate with our timing tool.
Wipeout
Age 11 to 16
Challenge Level
Can you do a little mathematical detective work to figure out which number has been wiped out?
Unequal Averages
Age 11 to 14
Challenge Level
Play around with sets of five numbers and see what you can discover about different types of average...
NRICH is part of the family of activities in the Millennium Mathematics Project.