The volume of a sealed packet is 150 cm³. What will be the mass of the water displaced by this packet? 
(Density of water : 1 g/cm³)

Volume of the packet, V = 150 cm³

We know that when an object is partially or fully floating in fluid, it displaces an equal volume of fluid.

∴ Volume of water= 150 cm³

Mass of water displaced by the packet = Density of water $\times$Volume of water

∴ m_w = ρ_w $\times$ V

m_w = 1 $\times$ 150 = 150 g.