During 4 hours one winter afternoon, when the outside temperature was 10C, a house heated by electricity was kept at 21C with the expenditure of 50 kwh (kilowatt-hours) of electric energy. (a) What was the average energy leakage in joules per second (watts) through the walls of the house to the environment (the outside air and ground)? watts (b) The rate at which energy is transferred between two systems due to a temperature difference is often proportional to their temperature difference. Assuming this to hold in this case, if the house temperature had been kept at 24C (75.2F), how many kwh of electricity would have been consumed? i kwh