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Rudolff's Problem

A group of 20 people pay a total of £20 to see an exhibition. The admission price is £3 for men, £2 for women and 50p for children. How many men, women and children are there in the group?

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Three circular medallions fit in a rectangular box. Can you find the radius of the largest one?

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Square Mean

Is the mean of the squares of two numbers greater than, or less than, the square of their means?

Building Tetrahedra

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

Imagine putting together two triangles with a perimeter of 20, edge to edge. 

Can you now add a third triangle with the same perimeter?

And a fourth?