The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is -20°, the temperature of the surroundings to which it rejects heat is

The coefficient of performance of a refrigerator is α=T2T1-T2 where T1 and T2 are the temperatures of hot and cold reservoirs (in kelvin) respectively.  Here, α=5,T2=-20°C=-20+273 K=253 KT1=?∴  5=253 KT1-253 K5T1-5(253 K)=253 K5T1=253 K+5(253 K)=6(253 K)T1=65(253 K)=303.6 K=303.6-273=30.6°C≈31°C