Dear Student,
Buoyant force on boat is equal to the weight of water displaced by it, that is 6000 N.
Weight of boat is equal to the force exerted on it that is equal to 6000 N.
The buoyant force exerted by a liquid depends on the volume of the solid object immersed in the liquid.As the volume of the solid object immersed inside the liquid increases, the upward buoyant force also increases.