Question

It takes 56.5 kilojoules of energy to raise the temperature of 150 milliliters of water from 5°C to 95°C. If you

use an electric water heater that is 60% efficient, how many kilojoules of electrical energy will the heater
actually use by the time the water reaches its final temperature?

Answer 1

You'd get an extra 40/60 of the energy, or 2/3. Multiply 5/3 by the required energy to get the actual consumption.