A toy skyrocket consists of a solid conical top, $\rho_{i}=600 \mathrm{kg} / \mathrm{m}^{3},$ a hollow cylinder, $\rho_{c}=400 \mathrm{kg} / \mathrm{m}^{3},$ and a stick having a circular cross section, $\rho_{s}=300 \mathrm{kg} / \mathrm{m}^{3}$ Determine the length of the stick, $x,$ so that the center of gravity $G$ of the skyrocket is located along line $a a$.