Ratio and proportion

A male punky fish has 9 stripes and a female punky fish has 8 stripes. I count 86 stripes on the fish in my tank. What is the ratio of male fish to female fish?

Weekly Problem 37 - 2007
This regular hexagon has been divided into four trapezia and one hexagon.... what is the ratio of the lengths of sides p, q and r?

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.

The triangles in these sets are similar - can you work out the lengths of the sides which have question marks?

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

Imagine you were given the chance to win some money... and imagine you had nothing to lose...

Two right-angled triangles are connected together as part of a structure. An object is dropped from the top of the green triangle where does it pass the base of the blue triangle?

A new problem posed by Lyndon Baker who has devised many NRICH problems over the years.