. Water is leaking from a trough at the rate of 0.8 L/s. The trough has a trapezoidal cross section, where the width at the bottom is 55 cm, at the top is 85 cm, and the height is 25 cm. The length of the trough is 3 m. Find the rate at which the height is changing when the depth of water is 11 cm. (10 marks)