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.

Distance from light source (cm)Rate of photosynthesis (bubble per min)
10120
1554
2030
2517
3013

If we draw a graph of this data:

A graph showing the number of bubbles produced per minute.

Note that this graph is a curve.

Question

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

40 bubbles per minute.

Using the graph:

A graph showing the number of bubbles produced per minute.