Higher November 2024 Paper 6 Q19

19 This graph shows the depth of the water, in centimetres, at a particular point in a river over a period of 10 hours.

Graph of depth of the water in cm (0 to 40) against time from 9.00 to 19.00. The curve starts at 32 cm at 9.00, falls to a minimum of about 15.7 cm at about 12.30, rises slowly to 20 cm at 17.00 and then more steeply to 27 cm at 19.00
(a) Work out the average rate of change in the depth of the water over the 10 hours. [2]
(b) Use the graph to estimate the rate of change in the depth of the water at 17.00.
You must show working to support your estimate. [4]