Question

How many times longer is the diameter of a grain of sand than the diameter of the average cell in the human body? Show your work. If the diameter of a grain of sand is about 2 x 10-4 meters and the diameter of a human hair is about 0.000025 meters.

Answer 1

Diameter of grain of sand is = $2*10^{-4}$

Diameter of Human hair is = 0.000025

We can write it as = $2.5*10^{-5}$

So the ratio of diameter of grain of sand to diameter of human hair is 
= $\frac{2*10^{-4}}{2.5*10^{-5}}$ = 8

So we can say diameter of grain of sand is 8 times longer than the diameter of average cell in human body.