Working systematically

  • Put Out
    problem
    Favourite

    Put Out

    Age
    16 to 18
    Challenge level

    After transferring balls back and forth between two bags the probability of selecting a green ball from bag 2 is 3/5. How many green balls were in bag 2 at the outset?

  • Over-booking
    problem
    Favourite

    Over-Booking

    Age
    16 to 18
    Challenge level

    The probability that a passenger books a flight and does not turn up is 0.05. For an aeroplane with 400 seats how many tickets can be sold so that only 2% of flights are over-booked?

  • Counting on Letters
    problem

    Counting on Letters

    Age
    11 to 14
    Challenge level
    The letters of the word ABACUS have been arranged in the shape of a triangle. How many different ways can you find to read the word ABACUS from this triangular pattern?
  • Purr-fection
    problem

    Purr-Fection

    Age
    16 to 18
    Challenge level
    What is the smallest perfect square that ends with the four digits 9009?
  • Plum Tree
    problem

    Plum Tree

    Age
    14 to 18
    Challenge level
    Label this plum tree graph to make it totally magic!
  • W Mates
    problem

    W Mates

    Age
    16 to 18
    Challenge level
    Show there are exactly 12 magic labellings of the Magic W using the numbers 1 to 9. Prove that for every labelling with a magic total T there is a corresponding labelling with a magic total 30-T.
  • Spot the Card
    problem

    Spot the Card

    Age
    14 to 16
    Challenge level
    It is possible to identify a particular card out of a pack of 15 with the use of some mathematical reasoning. What is this reasoning and can it be applied to other numbers of cards?
  • Patchwork Quilt
    problem

    Patchwork Quilt

    Age
    7 to 14
    Challenge level
    Squares of the type shown are sewn together to make a quilt. How many different quilts can be made?
  • Magnetic personality
    problem

    Magnetic Personality

    Age
    7 to 16
    Challenge level
    60 pieces and a challenge. What can you make and how many of the pieces can you use creating skeleton polyhedra?
  • Cereal Packets
    problem

    Cereal Packets

    Age
    7 to 11
    Challenge level
    How can you put five cereal packets together to make different shapes if you must put them face-to-face?
Displaying 281 - 290 of 620