"The diagram below shows three kettles with their powers and the time they take to boil 500cm of water. How many units (kWh) does the 3kW kettle use to boil the water?"

The question above is about a diagram which shows 3 kettles. The one on the left is the on I have to focus on. The power of it is 3kW (KiloWatts) and its takes 3 minutes to boil the given amount of water. Can someone please answer this question? Don't give me an IP grabber or virus download link. If you give me a URL link of any kind, I will report your answer. Don't try it. The answer must be in kWh (KiloWatt Hours).​