Scientific calculations

The table shows a set of results obtained by students investigating the effect of light intensity on photosynthesis. They varied the distance of the plant from the light source.

In the table below, the Rate of photosynthesis = Number of bubbles produced per minute.

DistanceRate
10 cm120
15 cm54
20 cm30
25 cm17
30 cm13

If we draw a graph of this data:

A graph showing the number of bubbles produced per minute.
Question

From the graph, suggest the rate of oxygen production at 18 cm from the light source.

40 bubbles per minute.

Using the graph:

A graph showing the number of bubbles produced per minute.