P6 / Nan Hua / 2021 / SA2 / Paper 2 – Q15 [3 marks]

Question:

A tank was filled with some water. A tap was turned on and water flowed into the tank at a constant rate. After some time, another tap was turned on. Both taps were turned off after the tank was filled to the brim. The line graph shows the volume of water in the tank over this period of time.
(a) At which minute was the second tap turned on?
(b) How many litres of water flowed out from the second tap every minute?