A 1 metre cube has one face on the ground and one face against a
wall. A 4 metre ladder leans against the wall and just touches the
cube. How high is the top of the ladder above the ground?
Four rods are hinged at their ends to form a convex quadrilateral.
Investigate the different shapes that the quadrilateral can take.
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Black and White Socks
Age 14 to 16 Short Challenge Level
There are 20 black socks and $n$ white socks in a drawer.
When a sock is taken from the drawer, the probability that it is white is $\dfrac{1}{n}$.