In the image showing three cell types (bacterial cell 1 μm, skin cell 30 μm, palisade cell 0.04 mm), how many times longer is the skin cell compared to the bacterial cell?

This image shows three different types of cell. Bacterial cell - 1μm Skin cell - 30μm Palisade cell - 0.04mm

This image shows three different types of cell.

Bacterial cell - 1μm
Skin cell - 30μm
Palisade cell - 0.04mm

Answer

The skin cell is 30 times longer than the bacterial cell. This is because $30\,\mu m \div 1\,\mu m = 30$, and the $\mu m$ units cancel.

Explanation

What you are comparing

You are asked for a “how many times bigger” comparison, so you need a ratio:

$$\text{times longer} = \frac{\text{skin cell length}}{\text{bacterial cell length}}$$

Both lengths are already in micrometres:

$$\frac{30\,\mu m}{1\,\mu m} = 30$$

The units $\mu m$ cancel, leaving a pure number.

A result of 30 means the skin cell’s length is 30 times the bacterial cell’s length.