They are of unequal mass. Their masses are in the inverse ratio of the arms of the balance.

The bottom of the ship is made heavy so that the centre of gravity remains low. This ensures the stability of its equilibrium.

Acceleration of the rolling sphere,
a=gsinθ/((1+k²/R²))
Velocity of the sphere at the bottom of the inclined plane,
v=√(2gh/((1+k²/R²)))
The sphere will reach the bottom with the same speed v because h is the same in both the cases.