Ratio and proportion

  • Pi, a Very Special Number
    article

    Pi, a Very Special Number

    Read all about the number pi and the mathematicians who have tried to find out its value as accurately as possible.
  • Ratio or Proportion?
    article

    Ratio or Proportion?

    An article for teachers which discusses the differences between ratio and proportion, and invites readers to contribute their own thoughts.

  • Plane to See
    problem

    Plane to See

    Age
    16 to 18
    Challenge level
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    P is the midpoint of an edge of a cube and Q divides another edge in the ratio 1 to 4. Find the ratio of the volumes of the two pieces of the cube cut by a plane through PQ and a vertex.
  • Rule of Three
    problem
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    Rule of Three

    Age
    11 to 14
    Challenge level
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    If it takes four men one day to build a wall, how long does it take 60,000 men to build a similar wall?
  • Racing odds
    problem

    Racing Odds

    Age
    11 to 14
    Challenge level
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    In a race the odds are: 2 to 1 against the rhinoceros winning and 3 to 2 against the hippopotamus winning. What are the odds against the elephant winning if the race is fair?
  • Conical Bottle
    problem

    Conical Bottle

    Age
    14 to 16
    Challenge level
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    A right circular cone is filled with liquid to a depth of half its vertical height. The cone is inverted. How high up the vertical height of the cone will the liquid rise?
  • Circuit training
    problem

    Circuit Training

    Age
    14 to 16
    Challenge level
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    Mike and Monisha meet at the race track, which is 400m round. Just to make a point, Mike runs anticlockwise whilst Monisha runs clockwise. Where will they meet on their way around and will they ever meet at the start again? If so, after how many circuits?
  • Tuning and Ratio
    problem

    Tuning and Ratio

    Age
    16 to 18
    Challenge level
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    Why is the modern piano tuned using an equal tempered scale and what has this got to do with logarithms?
  • Six Notes all Nice Ratios
    problem

    Six Notes All Nice Ratios

    Age
    14 to 16
    Challenge level
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    The Pythagoreans noticed that nice simple ratios of string length made nice sounds together.