A kettle has a 55% energy efficiency. The input energy for the kettle is 378,000 J per boil. Calculate the amount of energy dissipated in 5 boils.

Energy used for one boil = (3.78 x 10⁵ / 100) x 55Energy used for one boil = 2.079 x 10⁵ J Energy lost per boil = 3.78 x 10⁵ -2.079 x 10⁵Energy lost per boil = 1.701 x 10⁵Energy lost per 5 boils = (1.701 x 10⁵) x 5Energy lost per 5 boils = 8.51 x 10⁵ J, 3 s.f. (or 851 kJ)