This picture is taken from the Problem Pictures resource of photographs with activities for mathematics teaching.
If you purchase this resource the photographs are available in higher resolution and there are additional pages containing hints and solutions.
The horizontal bar in the photograph has holes spaced 10 cm apart for the hoops to pass through. One hoop is 30 cm wide.
How many hoops would you need to make a railing that is 250 cm long?
Can you find a rule that gives the length of railing for any given number of hoops?