Representation of data — practice question

A smooth hemispherical shell, centred at $O$, has weight $12\,\text{N}$ and radius $0.4\,\text{m}$, and is resting on a horizontal plane. A particle of weight $W\,\text{N}$ is in equilibrium on the inside surface of the hemisphere directly below $O$. A vertically upward force of magnitude $F\,\text{N}$ is applied at the topmost point of the hemisphere, and the system is in equilibrium with its axis of symmetry at an angle of $20^\circ$ to the horizontal (see diagram).