Ratio and proportion

  • 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?

  • A Shade Crossed
    problem

    A Shade Crossed

    Age
    14 to 16
    Challenge level
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    Find the area of the shaded region created by the two overlapping triangles in terms of a and b?

  • ArRh!
    problem

    ArRh!

    Age
    14 to 16
    Challenge level
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    Triangle ABC is equilateral. D, the midpoint of BC, is the centre of the semi-circle whose radius is R which touches AB and AC, as well as a smaller circle with radius r which also touches AB and AC. What is the value of r/R?

  • 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.

  • A Scale for the Solar System
    problem

    A Scale for the Solar System

    Age
    14 to 16
    Challenge level
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    The Earth is further from the Sun than Venus, but how much further? Twice as far? Ten times?

  • Punky Fish
    problem

    Punky Fish

    Age
    14 to 16
    Challenge level
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    A male punky fish has 9 stripes and a female punky fish has 8 stripes. I count 86 stripes on the fish in my tank. What is the ratio of male fish to female fish?

  • Mixed up mixture
    problem

    Mixed Up Mixture

    Age
    14 to 16
    Challenge level
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    Can you fill in the mixed up numbers in this dilution calculation?

  • Meeting Point
    problem

    Meeting Point

    Age
    14 to 16
    Challenge level
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    Malcolm and Nikki run at different speeds. They set off in opposite directions around a circular track. Where on the track will they meet?

  • Tennis Club
    problem

    Tennis Club

    Age
    14 to 16
    Challenge level
    filled star empty star empty star

    Three-quarters of the junior members of a tennis club are boys and the rest are girls. What is the ratio of boys to girls among these members?

  • Contact
    problem

    Contact

    Age
    14 to 16
    Challenge level
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    A circular plate rolls in contact with the sides of a rectangular tray. How much of its circumference comes into contact with the sides of the tray when it rolls around one circuit?