How Do You Calculate the Efficiency of a 2.5kW Electric Kettle?

[firemama]

Homework Statement

A 2.5kW electric kettle takes 3 mins to raise the temperature of 1.2kg of water from a temperature of 20 degrees C to a temperature of 100 degress. The specific heat capacity of water is 4.2kJ/(kg K)

Homework Equations

So far I know that we're either using P=vit ot Q=mct
How do i find:
(a) enerygy output from 2.5kW heating element in a time of 3 mins, (b) efficiency of the heating.

 

[mgb_phys]

A kw is 1000 J/second

Calculate how much energy it took to heat the water and compare that with the answer from A