1. Sphere inner core radius 3490km and density 13000kg/m3. Outer radius 6400km and density 4000kg/m3. Show that the moment of inertia is approximately 8 x 1037kg m2. 2. I know that the moment of inertia of a sphere is 2/5xmr2. 3. I have calculated the volume for each part of the sphere using 4/3∏r3. Then used the equation in part 2 to calculate the moment of inertia for the inner and outer parts of the sphere. I have read that for more complex shapes the moments of inertia need to be added together to give the total moment of inertia, however this only gives 7.2 x 1037kg m2. Is there some formula I am missing because I have tried calculating each mass and adding them together and using the outer radius for the calculation and then used a mean radius for the calculation but nothing remotely close to the required answer of 8 x 1037. Any guidance would be appreciated as I can do the maths. Just think I am missing something vital.