g/cm3 or 0.1992 lb/in3. You can arrive at this answer through these steps:
The mass of the Earth is 5.97237 ×1024 kg, and its volume is 1.08321 ×1012 km3.
Divide the mass of the Earth by its volume to get its density, 5,514 ×10-9 kg/km3, which is equal to 5.514 g/cm3.
Congratulations, you've calculated the mean density of the Earth!
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