Other tags that relate to Cobalt Decay
Simultaneous equations. Maths Supporting SET. Estimating and approximating. Engineering. Chemistry. Investigations. Physics. Ratio and proportion. Exponential and Logarithmic Functions. Biology.There are 66 results
Broad Topics > Fractions, Decimals, Percentages, Ratio and Proportion > Ratio and proportion
Diamonds Aren't Forever
Age 16 to 18 Challenge Level:
Ever wondered what it would be like to vaporise a diamond? Find out inside...
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.
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.
Gassy Information
Age 16 to 18 Challenge Level:
Do each of these scenarios allow you fully to deduce the required facts about the reactants?
Reductant Ratios
Age 16 to 18 Challenge Level:
What does the empirical formula of this mixture of iron oxides tell you about its consituents?
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?
Mixed up Mixture
Age 14 to 16 Challenge Level:
Can you fill in the mixed up numbers in this dilution calculation?
Exact Dilutions
Age 14 to 16 Challenge Level:
Which exact dilution ratios can you make using only 2 dilutions?
Investigating the Dilution Series
Age 14 to 16 Challenge Level:
Which dilutions can you make using only 10ml pipettes?
Dilution Series Calculator
Age 14 to 16 Challenge Level:
Which dilutions can you make using 10ml pipettes and 100ml measuring cylinders?
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.
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
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?
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.
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?
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?
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.
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. . . .
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.
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?
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?
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?
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?
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.
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. . . .
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?
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?
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?
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?
Two Ladders
Age 14 to 16 Challenge Level:
Two ladders are propped up against facing walls. The end of the first ladder is 10 metres above the foot of the first wall. The end of the second ladder is 5 metres above the foot of the second. . . .
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.
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?
One and Three
Age 14 to 16 Challenge Level:
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. . . .
Sitting Pretty
Age 14 to 16 Challenge Level:
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?
NRICH is part of the family of activities in the Millennium Mathematics Project.