9700/12 Biology May Jun 2020 Online Test | Cambridge AS and A Level MCQ

A student used a potometer to measure the rate of water loss from a plant by transpiration.
The internal diameter of the capillary tube and the distance moved by the bubble in 30 seconds were recorded.
The results are shown in the table.
The volume of water moved $ = \pi {r^2} \times $ distance moved by the bubble.
Which calculation correctly shows how to determine the rate of transpiration…