Ratio and proportion

  • Two Ladders
    problem
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    Two Ladders

    Age
    14 to 16
    Challenge level
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    Two ladders are propped up against facing walls. At what height do the ladders cross?

  • Sitting Pretty
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    Sitting Pretty

    Age
    14 to 16
    Challenge level
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    A circle of radius r touches two sides of a right angled triangle, sides x and y, and has its centre on the hypotenuse. Can you prove the formula linking x, y and r?

  • Triangle in a Triangle
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    Triangle in a Triangle

    Age
    14 to 16
    Challenge level
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    Can you work out the fraction of the original triangle that is covered by the inner triangle?

  • Trapezium Four
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    Trapezium Four

    Age
    14 to 16
    Challenge level
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    The diagonals of a trapezium divide it into four parts. Can you create a trapezium where three of those parts are equal in area?

  • Speeding boats
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    Speeding Boats

    Age
    14 to 16
    Challenge level
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    Two boats travel up and down a lake. Can you picture where they will cross if you know how fast each boat is travelling?

  • Golden Thoughts
    problem
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    Golden Thoughts

    Age
    14 to 16
    Challenge level
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    Rectangle PQRS has X and Y on the edges. Triangles PQY, YRX and XSP have equal areas. Prove X and Y divide the sides of PQRS in the golden ratio.
  • Mixing More Paints
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    Mixing More Paints

    Age
    14 to 16
    Challenge level
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    Can you find an efficent way to mix paints in any ratio?

  • Ratios and Dilutions
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    Ratios and Dilutions

    Age
    14 to 16
    Challenge level
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    Scientists often require solutions which are diluted to a particular concentration. In this problem, you can explore the mathematics of simple dilutions
  • Areas and Ratios
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    Areas and Ratios

    Age
    16 to 18
    Challenge level
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    Do you have enough information to work out the area of the shaded quadrilateral?

  • 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.