Weekly Problem 13 - 2014
A bag contains red, orange, green and blue marbles. How many need to be taken out to ensure that at least three are of the same colour?
Weekly Problem 37 - 2009
Sam is holding two lengths of rope, and Pat ties two of the loose ends at random. What ropes could they end up with, and with what probability?
Weekly Problem 9 - 2014
What is the smallest number of jelly babies Matt needs to remove from his pocket to guarentee he gets at least one of each flavour?
Weekly Problem 47 - 2012
Three monkeys each hung up their hats as they entered a cafe. They each took a hat at random when they left. What is the probability that they all took the correct hats?