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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.


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?


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?

Age 16 to 18
Challenge Level
Decide on the unknowns and assign letters to them. Take the information given step by stepand write down expressions for the probabilities. Can you obtain an equation and solve it?