A piece of wood floats in water, submerged by 3/4 of its volume. What is the density of the tree?

V1 = (3/4) * V.
ρv = 1000 kg / m ^ 3.
g = 9.8 m / s ^ 2.
ρд -?
Two forces act on a body immersed in water: the force of gravity Ft = m * g and the force of Archimedes Farch = ρw * g * V1.
Since the body is at rest, these forces are equal to each other.
m * g = ρw * g * V1.
m = ρд * V.
ρd * V * g = ρw * g * V1.
ρd * V * g = ρw * g * (3/4) * V.
ρд = ρв * 3/4.
ρd = 1000 kg / m ^ 3 * 3/4 = 750 kg / m ^ 3.
Answer: wood density ρd = 750 kg / m ^ 3.