Exploring maths through problem solving

Problem of the Week

Amazing Nature

This photograph shows an experiment by kindergarten children. They dropped seeds into the crack at the side of the footpath to see what would happen.

If you only had this photograph, how would you make the most reliable estimate of the average number of plants per section of footpath?


There are several ways in which this estimate could be made from the photograph, though clearly, being physically able to count and measure would be much more reliable than making an estimate from a photograph.

I would only use the part of the photograph where the count is more reliable (so not the back sections).

I would also not choose the front section because you can’t see all of it.

I would use the lengths that can be seen more reliably. This would be the sections of the gutter, rather than the sections of the footpath.

There look to be 3 footpath sections to every gutter section.

Using my method, there are 5 gutter sections so this is 5 x 3 = 15 footpath sections.

I counted about 9 plants within these sections.

This makes the estimate:  9 ÷ 15 = 9 fifteenths of a plant per footpath section.

Which is 3 fifths of a plant per footpath section.

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