A Sudoku with clues as ratios or fractions.
The scale on a piano does something clever : the ratio (interval) between any adjacent points on the scale is equal. If you play any note, twelve points higher will be exactly an octave on.
A Sudoku with clues as ratios.
Anne completes a circuit around a circular track in 40 seconds. Brenda runs in the opposite direction and meets Anne every 15 seconds. How long does it take Brenda to run around the track?
Using an understanding that 1:2 and 2:3 were good ratios, start with a length and keep reducing it to 2/3 of itself. Each time that took the length under 1/2 they doubled it to get back within range.
A Sudoku with clues as ratios.
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. . . .
Imagine you were given the chance to win some money... and imagine you had nothing to lose...
What is the ratio of the area of a square inscribed in a semicircle to the area of the square inscribed in the entire circle?
Four jewellers share their stock. Can you work out the relative values of their gems?
Some of the numbers have fallen off Becky's number line. Can you figure out what they were?
Points P, Q, R and S each divide the sides AB, BC, CD and DA respectively in the ratio of 2 : 1. Join the points. What is the area of the parallelogram PQRS in relation to the original rectangle?
The Pythagoreans noticed that nice simple ratios of string length made nice sounds together.
The large rectangle is divided into a series of smaller quadrilaterals and triangles. Can you untangle what fractional part is represented by each of the ten numbered shapes?
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?
Find the ratio of the outer shaded area to the inner area for a six pointed star and an eight pointed star.
Can you find an efficent way to mix paints in any ratio?
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?
Can you work out how to produce different shades of pink paint?
At the beginning of the night three poker players; Alan, Bernie and Craig had money in the ratios 7 : 6 : 5. At the end of the night the ratio was 6 : 5 : 4. One of them won $1 200. What were the. . . .
Two boats travel up and down a lake. Can you picture where they will cross if you know how fast each boat is travelling?
Two motorboats travelling up and down a lake at constant speeds leave opposite ends A and B at the same instant, passing each other, for the first time 600 metres from A, and on their return, 400. . . .
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. . . .
If the sides of the triangle in the diagram are 3, 4 and 5, what is the area of the shaded square?
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?
Mainly for teachers. More mathematics of yesteryear.
A trapezium is divided into four triangles by its diagonals. Can you work out the area of the trapezium?
An article for teachers which discusses the differences between ratio and proportion, and invites readers to contribute their own thoughts.
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.
A garrison of 600 men has just enough bread ... but, with the news that the enemy was planning an attack... How many ounces of bread a day must each man in the garrison be allowed, to hold out 45. . . .
How long will it take Mary and Nigel to wash an elephant if they work together?
Can you fill in the mixed up numbers in this dilution calculation?
One night two candles were lit. Can you work out how long each candle was originally?
A farmer is supplying a mix of seeds, nuts and dried apricots to a manufacturer of crunchy cereal bars. What combination of ingredients costing £5 per kg could he supply?
Take any rectangle ABCD such that AB > BC. The point P is on AB and Q is on CD. Show that there is exactly one position of P and Q such that APCQ is a rhombus.
If it takes four men one day to build a wall, how long does it take 60,000 men to build a similar wall?
Can you work out which drink has the stronger flavour?
What's the most efficient proportion for a 1 litre tin of paint?
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. . . .
Which dilutions can you make using 10ml pipettes and 100ml measuring cylinders?
Move the point P to see how P' moves. Then use your insights to calculate a missing length.
My recipe is for 12 cakes - how do I change it if I want to make a different number of cakes?
Can you work out the fraction of the original triangle that is covered by the inner triangle?
Is there a temperature at which Celsius and Fahrenheit readings are the same?
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. . . .
Scientists often require solutions which are diluted to a particular concentration. In this problem, you can explore the mathematics of simple dilutions
In the ancient city of Atlantis a solid rectangular object called a Zin was built in honour of the goddess Tina. Your task is to determine on which day of the week the obelisk was completed.
Two right-angled triangles are connected together as part of a structure. An object is dropped from the top of the green triangle where does it pass the base of the blue triangle?
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. . . .
Which is a better fit, a square peg in a round hole or a round peg in a square hole?