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Four vehicles travelled on a road. What can you deduce from the times that they met?

A Scale for the Solar System

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


Swimmers in opposite directions cross at 20m and at 30m from each end of a swimming pool. How long is the pool ?


Age 14 to 16
Challenge Level

This problem offers opportunities to think about the properties of regular shapes and decide which do, and which do not, affect the result.

There is also opportunity for geometric reasoning based on area, but saying any more about that would give away too much about one route through the problem !