The radius of the Earth is approximately 6370 km. if one could dig down straight towards the center of the Earth, one would find that the innermost 3480 km (the core) has an average density of about 11.g/cm^3 Above that are the mantle and crust. if the average density of the Earth is 5.5 g/cm^3, what is the average density of the Earth's mantle and crust?