A Solar Heated House Loses About 5

A solar heated house loses about 5.2 × 10⁷ cal through its outer surfaces on a typical 24-h winter day.What mass of storage rock is needed to provide this amount of heat if it is brought up to initial temperature of 66°C by the solar collectors and the house is maintained at 21°C? (Specific heat of rock is 0.21 cal/g⋅°C. )
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A) 1,100 kg
B) 55,000 kg
C) 5,500 kg
D) 600 kg
E) ​1,200 kg