### Rain or Shine

Predict future weather using the probability that tomorrow is wet given today is wet and the probability that tomorrow is wet given that today is dry.

### Knock-out

Before a knockout tournament with 2^n players I pick two players. What is the probability that they have to play against each other at some point in the tournament?

### Squash

If the score is 8-8 do I have more chance of winning if the winner is the first to reach 9 points or the first to reach 10 points?

# How Many Balls?

##### Stage: 5 Challenge Level:

A bag contains an assortment of red and blue balls. Two balls are drawn at random.

You are told that the probability of drawing two red balls is 5 times the probability of drawing two blue balls. Furthermore, the probability of drawing one ball of each colour is 6 times the probability of drawing two blue balls.

How many blue and how many red balls are in the bag?