Question

A student measured the numbers of stomata per mm of leaf

surface. Their counts were: 250, 280, 265, 245, 270, 255, 290.
Calculate the mean number of stomata (to 3 significant
figures).
​

Answer 1

When we have a set of N numbers like:

{x₁, x₂, ..., xₙ}

The mean of the set is:

M = (x₁ + x₂ + ... + xₙ)/N

In this case, we have the set:

{250, 280, 265, 245, 270, 255, 290}

So we have a set of 7 elements.

The mean of this set will be:

M = (250 + 280 + 265 + 245 + 270 + 255 + 290)/7 = 1855/7 = 265

So the mean number of stomata per mm of leaf surface is 265.