How many times is the mass of an iron ball greater than the mass of a ball of the same size made of aluminum?

The mass of any of the balls can be calculated using the formula:
m = ρ * V, where m is the mass of the ball (kg), ρ is the density of the material from which the ball is made (kg / m³), V is the volume of the ball (m³).
Iron ball weight:
m1 = ρ1 * V1, where ρ1 = 7800 kg / m³.
Aluminum ball weight:
m2 = ρ2 * V2, where ρ2 = 2700 kg / m³.
From the conditions of the problem: V1 = V2.
m1 / m2 = ρ1 * V1 / (ρ2 * V2) = ρ1 / ρ2 = 7800/2700 = 2.89.
Answer: The mass of the iron ball will be 2.89 times the mass of the aluminum ball.