(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

What is the average density of rock in the mantle? The earth's average density is 5500 kg/m^3; the radius of the core is 3490 km; ratio of core density to mantle density is 2.34

2. Relevant equations

Pc = density core

Pm = density mantle

Pe = density earth

Mm = mass mantle

Mc = mass core

Rm = radius mantle

Pc/Pm = 2.34 so Pc/2.34=Pm

Pm = Mm/(4/3)*pi*Rm^3

Pc = Mc/(4/3)*pi*(3.49E6)^3

Rm = Re - Rc

Assume only the core and mantle compose the earth.

Mc/Vc + Mm/Vm = Me/Ve = Pe = 5500 (?)

3. The attempt at a solution

Pc/2.34 = Pm = (Mc/(4/3)*pi*(3.49E6)^3)/2.34

I'm not sure what equation would give me Mc, the mass of the core. My other equation had the radius of the earth as a variable. I think I'm just missing one equation, but I can't seem to find another relationship.

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# Homework Help: Density of Earth's Mantle w/o knowing radius

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