Ratio and proportion

problem
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.
problem
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?
problem
Tyre wear

Age

11 to 14

Challenge level

A car with 5 tyres (four road tyres and a spare) travelled 30,000 km. All 5 tyres were used equally. How many kilometres' wear did each tyre receive?
problem
Meeting point

Age

14 to 16

Challenge level

Malcolm and Nikki run at different speeds. They set off in opposite directions around a circular track. Where on the track will they meet?
problem
Extreme dissociation

Age

16 to 18

Challenge level

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

Age

14 to 16

Challenge level

Which exact dilution ratios can you make using only 2 dilutions?
problem
Investigating the dilution series

Age

14 to 16

Challenge level

Which dilutions can you make using only 10ml pipettes?
problem
Dilution series calculator

Age

14 to 16

Challenge level

Which dilutions can you make using 10ml pipettes and 100ml measuring cylinders?
problem
Mixed up mixture

Age

14 to 16

Challenge level

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

Age

11 to 14

Challenge level

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.