Probability

  • What's the point of squash?
    problem

    What's the point of squash?

    Age
    14 to 18
    Challenge level
    filled star empty star empty star
    Under which circumstances would you choose to play to 10 points in a game of squash which is currently tied at 8-all?
  • Genetics
    problem

    Genetics

    Age
    14 to 16
    Challenge level
    filled star empty star empty star
    A problem about genetics and the transmission of disease.
  • How Risky \is my diet?
    problem

    How risky is my diet?

    Age
    11 to 16
    Challenge level
    filled star filled star empty star
    Newspapers said that eating a bacon sandwich every day raises the risk of bowel cancer by 20%. Should you be concerned?
  • Statins and Risk
    problem

    Statins and risk

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    "Statins cut the risks of heart attacks and strokes by 40%"
    Should the Professor take statins? Can you help him decide?
  • Knock-out
    problem

    Knock-out

    Age
    16 to 18
    Challenge level
    filled star filled star empty star
    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?
  • Coin Tossing Games
    problem

    Coin tossing games

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    You and I play a game involving successive throws of a fair coin. Suppose I pick HH and you pick TH. The coin is thrown repeatedly until we see either two heads in a row (I win) or a tail followed by a head (you win). What is the probability that you win?
  • Win or Lose?
    problem

    Win or lose?

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    A gambler bets half the money in his pocket on the toss of a coin, winning an equal amount for a head and losing his money if the result is a tail. After 2n plays he has won exactly n times. Has he more money than he started with?
  • Thank your Lucky Stars
    problem

    Thank your lucky stars

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    A counter is placed in the bottom right hand corner of a grid. You toss a coin and move the star according to the following rules: ... What is the probability that you end up in the top left-hand corner of the grid?
  • Master Minding
    problem

    Master minding

    Age
    11 to 14
    Challenge level
    filled star filled star empty star
    Your partner chooses two beads and places them side by side behind a screen. What is the minimum number of guesses you would need to be sure of guessing the two beads and their positions?
  • Voting Paradox
    problem

    Voting paradox

    Age
    14 to 18
    Challenge level
    filled star filled star empty star
    Some relationships are transitive, such as `if A>B and B>C then it follows that A>C', but some are not. In a voting system, if A beats B and B beats C should we expect A to beat C?