The image below shows three kettles with their power ratings and the time they take to boil 500cm3 of water. How many units (kWh) does the 2.2kW kettle use to boil the water? Give your answer to 2 decimal places.

The number of units does the 2.2kW kettle use to boil the water is 0.13 KWh.

Given that,  

here we have to convert 3.5 minutes to hour.  

since

60 mins = 1 hour

Therefore, 3.5 mins =  0.058 hour

Now

So,  

= 2.2 (0.058)

= 0.13 KWh.

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0.13 KWh.

Explanation:

The following data were obtained from the question:

Power = 2.2KW

Time = 3.5 minutes

Next, we convert 3.5 minutes to hour. This is illustrated below:

60 mins = 1 hour

Therefore, 3.5 mins = 3.5/60 = 0.058 hour

Now, we can obtain the energy in KWh as follow:

Power = 2.2KW

Time = 0.058 hour

Energy =?

Power = Energy / time

Cross multiply

Energy = Power x time

Energy = 2.2 x 0.058

Energy = 0.13 KWh.

Therefore, it will take 0.13 KWh for the 2.2KW kettle to boil the water.