Having trouble finding the center of mass for multiple objects

[kavamo]

Homework Statement

Find the x-coordinate of the center of mass of the composite object shown in the figure. The sphere, cylinder, and rectangular solid all have a uniform composition. Their masses and dimensions are: sphere: 200 g, diameter = 10 cm; cylinder: 450 g, length = 11 cm, radius = 5.0 cm; rectangular solid: m = 220 g, length in x-direction = 16 cm, height = 10 cm, depth = 12 cm.

Homework Equations

using the formula: x1m1+x2m2+x3m3 / Total mass of objects

The Attempt at a Solution

200(10) + 11(450) + 16(220) / 870 = 12.0346

what am I missing/doing wrong?

 

[rock.freak667]

In the formula

M \bar{x}=m_1x_1+m_2x_2+m_3x_3

x₁,x₂ and x₃ are the centroids of the masses m₁, m₂ and m₃ respectively.

I don't think the centroid of a sphere is at the end of its diameter.