Final answer:
By dividing the total volume of water wasted (180 litres) by the flow rate of the faucet (15 liters per minute), we find that the faucet was left running for 12 minutes.
Step-by-step explanation:
To calculate the time the faucet was left running, we can use the following equation:
Time = Total Volume Wasted / Flow Rate
Given that the faucet wastes 15 litres of water per minute, and there was a total of 180 litres of water wasted, we can insert these values into the equation:
Time = 180 litres / 15 litres per minute = 12 minutes
Therefore, the faucet was left running for 12 minutes to waste 180 litres of water.