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)