Assume that a spherical cell, with a diameter of 18 μm, has spherical mitochondria, each with a diameter of 0.18 μm. If mitochondria occupy 13.4% of the volume of the cell, how many mitochondria are there?

Since the linear dimension of the mitochondria is 10^-2 times that of the cell, the volume as a proportion of cell volume will be (10^-2) ^3 = 10^-6. In order to make up 0.134 of the cell volume, there must be

(1.34*10^-1) / (10^-6) = 1.34*10^5

mitochondria in the cell.

There are about 134,000 mitochondria.