A household refrigerator that has a power input of 450 W and a COP of 2.5 is tocool five large watermelons, 10 kg each, to 8C.

A household refrigerator that has a power input of 450 W and a COP of 2.5 is tocool five large watermelons, 10 kg each, to 8°C. If the watermelons are initially at 20°C,determine how long it will take for the refrigerator to cool them. The watermelons canbe treated as water whose specific heat is 4.2 kJ/kg · °C. Is your answer realistic oroptimistic? Explain