Chemistry
posted by ALISON .
The mass of the earth is known to be about 5.98 X10^24kg assume that it is approx. spherical with an average diameter of 1.276X10^7 METERS. from these data calculate the average density of the earth(g/cm^3) could the earth be made mostly of water (density=1.00g/cm^3), abundant elements like calcium silicate (density=3.27g/cm^3) or aluminum oxide(density=4.0g/cm^3)?
How do I explain this????What hypothesis would explain why the earth has a considerably higher density than any of these materials, which are abundant at the surface of the earth???
i got 2.88g/cm^3 for the earths density. is that right?

I did not get 2.88 g/cc as a density but I could have made an error.
I used 4/3(*pi*r^3) for volume and converted diameter in m to cm first.
I converted mass in kg to grams first.
For the explanation, what is the core of the earth. If that is made of something much more dense it would make the overall density more than the surface area. Post your work if you want me to check the density calculation. 

See this link for the inner core.
http://en.wikipedia.org/wiki/Earth