#### (a) Calculate the number of cells in a hummingbird assuming the mass of an average cell is ten times the mass of a bacterium.

#### (b) Making the same assumption, how many cells are there in a human?

## Solution:

### Part a

The mass of a hummingbird is 10^{-2} kg, while the mass of a cell is 10^{-15} kg. The number of cells in the hummingbird is

### Part b

The mass of a person is 10^{2} kg.