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The info below shows three kettles with their powers and the time they take to boil 500cm3 of water. If electricity costs 9p per unit, how much does it cost to boil 500cm3 of water using the 3kW kettle?
Kettle 1= 3mins =3kW
Kettle 2= 3.5mins= 2.2kW
Kettle 3=4.5mins=1.4kW
Any help would be appreciated!