problem
Favourite
In a box
Age
14 to 16
Challenge level
Chris and Jo put two red and four blue ribbons in a box. They each pick a ribbon from the box without looking. Jo wins if the two ribbons are the same colour. Is the game fair?
problem
Favourite
Odds and evens
Age
11 to 14
Challenge level
Are these games fair? How can you tell?
problem
Favourite
Substitution cipher
Age
11 to 14
Challenge level
Find the frequency distribution for ordinary English, and use it to help you crack the code.
problem
Favourite
Wipeout
Age
11 to 16
Challenge level
Can you do a little mathematical detective work to figure out which number has been wiped out?
problem
Favourite
M, M and M
Age
11 to 14
Challenge level
If you are given the mean, median and mode of five positive whole numbers, can you find the numbers?