Resources tagged with: Ratio and proportion

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There are 66 results

Broad Topics > Fractions, Decimals, Percentages, Ratio and Proportion > Ratio and proportion

Why Multiply When You're about to Divide?

Age 16 to 18
Challenge Level

A brief introduction to PCR and restriction mapping, with relevant calculations...

Extreme Dissociation

Age 16 to 18
Challenge Level

In this question we push the pH formula to its theoretical limits.

Diamonds Aren't Forever

Age 16 to 18
Challenge Level

Ever wondered what it would be like to vaporise a diamond? Find out inside...

Mixed up Mixture

Age 14 to 16
Challenge Level

Can you fill in the mixed up numbers in this dilution calculation?

Reductant Ratios

Age 16 to 18
Challenge Level

What does the empirical formula of this mixture of iron oxides tell you about its consituents?

Striking Gold

Age 16 to 18
Challenge Level

Investigate some of the issues raised by Geiger and Marsden's famous scattering experiment in which they fired alpha particles at a sheet of gold.

Eudiometry

Age 16 to 18
Challenge Level

When a mixture of gases burn, will the volume change?

Gassy Information

Age 16 to 18
Challenge Level

Do each of these scenarios allow you fully to deduce the required facts about the reactants?

Dilution Series Calculator

Age 14 to 16
Challenge Level

Which dilutions can you make using 10ml pipettes and 100ml measuring cylinders?

Exact Dilutions

Age 14 to 16
Challenge Level

Which exact dilution ratios can you make using only 2 dilutions?

Tuning and Ratio

Age 16 to 18
Challenge Level

Why is the modern piano tuned using an equal tempered scale and what has this got to do with logarithms?

Investigating the Dilution Series

Age 14 to 16
Challenge Level

Which dilutions can you make using only 10ml pipettes?

The Fastest Cyclist

Age 14 to 16
Challenge Level

Andy is desperate to reach John o'Groats first. Can you devise a winning race plan?

Ratios and Dilutions

Age 14 to 16
Challenge Level

Scientists often require solutions which are diluted to a particular concentration. In this problem, you can explore the mathematics of simple dilutions

Eight Ratios

Age 14 to 16
Challenge Level

Two perpendicular lines lie across each other and the end points are joined to form a quadrilateral. Eight ratios are defined, three are given but five need to be found.

Halving the Triangle

Age 16 to 18
Challenge Level

Draw any triangle PQR. Find points A, B and C, one on each side of the triangle, such that the area of triangle ABC is a given fraction of the area of triangle PQR.

Roasting Old Chestnuts 3

Age 11 to 16

Mainly for teachers. More mathematics of yesteryear.

Six Notes All Nice Ratios

Age 14 to 16
Challenge Level

The Pythagoreans noticed that nice simple ratios of string length made nice sounds together.

Another Triangle in a Triangle

Age 16 to 18
Challenge Level

Can you work out the fraction of the original triangle that is covered by the green triangle?

Five Circuits, Seven Spins

Age 16 to 18
Challenge Level

A circular plate rolls inside a rectangular tray making five circuits and rotating about its centre seven times. Find the dimensions of the tray.

Burning Down

Age 14 to 16
Challenge Level

One night two candles were lit. Can you work out how long each candle was originally?

Make Your Own Solar System

Age 7 to 16
Challenge Level

Making a scale model of the solar system

Bus Stop

Age 14 to 16
Challenge Level

Two buses leave at the same time from two towns Shipton and Veston on the same long road, travelling towards each other. At each mile along the road are milestones. The buses' speeds are constant. . . .

Nutrition and Cycling

Age 14 to 16
Challenge Level

Andy wants to cycle from Land's End to John o'Groats. Will he be able to eat enough to keep him going?

A Scale for the Solar System

Age 14 to 16
Challenge Level

The Earth is further from the Sun than Venus, but how much further? Twice as far? Ten times?

All about Ratios

Age 16 to 18
Challenge Level

A new problem posed by Lyndon Baker who has devised many NRICH problems over the years.

Rarity

Age 16 to 18
Challenge Level

Show that it is rare for a ratio of ratios to be rational.

Conical Bottle

Age 14 to 16
Challenge Level

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?

Tin Tight

Age 14 to 16
Challenge Level

What's the most efficient proportion for a 1 litre tin of paint?

Chord

Age 16 to 18
Challenge Level

Equal touching circles have centres on a line. From a point of this line on a circle, a tangent is drawn to the farthest circle. Find the lengths of chords where the line cuts the other circles.

Plane to See

Age 16 to 18
Challenge Level

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.

Golden Ratio

Age 16 to 18
Challenge Level

Solve an equation involving the Golden Ratio phi where the unknown occurs as a power of phi.

Slippage

Age 14 to 16
Challenge Level

A ladder 3m long rests against a wall with one end a short distance from its base. Between the wall and the base of a ladder is a garden storage box 1m tall and 1m high. What is the maximum distance. . . .

Ratio Sudoku 2

Age 11 to 16
Challenge Level

A Sudoku with clues as ratios.

Points in Pairs

Age 14 to 16
Challenge Level

Move the point P to see how P' moves. Then use your insights to calculate a missing length.

Mixing More Paints

Age 14 to 16
Challenge Level

Can you find an efficent way to mix paints in any ratio?

Speeding Boats

Age 14 to 16
Challenge Level

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

Orbiting Billiard Balls

Age 14 to 16
Challenge Level

What angle is needed for a ball to do a circuit of the billiard table and then pass through its original position?

Triangle in a Triangle

Age 14 to 16
Challenge Level

Can you work out the fraction of the original triangle that is covered by the inner triangle?

Circuit Training

Age 14 to 16
Challenge Level

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. . . .

At a Glance

Age 14 to 16
Challenge Level

The area of a regular pentagon looks about twice as a big as the pentangle star drawn within it. Is it?

Pent

Age 14 to 18
Challenge Level

The diagram shows a regular pentagon with sides of unit length. Find all the angles in the diagram. Prove that the quadrilateral shown in red is a rhombus.

Around and Back

Age 14 to 16
Challenge Level

A cyclist and a runner start off simultaneously around a race track each going at a constant speed. The cyclist goes all the way around and then catches up with the runner. He then instantly turns. . . .

Golden Thoughts

Age 14 to 16
Challenge Level

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.

Napoleon's Hat

Age 16 to 18
Challenge Level

Three equilateral triangles ABC, AYX and XZB are drawn with the point X a moveable point on AB. The points P, Q and R are the centres of the three triangles. What can you say about triangle PQR?

Gift of Gems

Age 14 to 16
Challenge Level

Four jewellers share their stock. Can you work out the relative values of their gems?

Areas and Ratios

Age 16 to 18
Challenge Level

Do you have enough information to work out the area of the shaded quadrilateral?

Trapezium Four

Age 14 to 16
Challenge Level

The diagonals of a trapezium divide it into four parts. Can you create a trapezium where three of those parts are equal in area?

From All Corners

Age 14 to 16
Challenge Level

Straight lines are drawn from each corner of a square to the mid points of the opposite sides. Express the area of the octagon that is formed at the centre as a fraction of the area of the square.

Same Height

Age 14 to 16
Challenge Level

A trapezium is divided into four triangles by its diagonals. Can you work out the area of the trapezium?