Aheat pump supplies heat to a house at the rate of 150,000 kj/h when the house is maintained at 25˚c. over the period of one month, the heat pump operates for 120 hours to transfer energy from a heat source outside the house to the inside the house. consider two different outside sources: the first is the outside air at -3˚c and the second is a lake at 7˚. if electricity costs $0.06/kwh, determine the maximum money saved by using the lake water rather than the outside air as the outside energy source.