Which cast iron weight weighing 5 kg or 20 kg has more volume and how many times?

The volume of a cast iron weight can be calculated using the formula:
V = m / ρ, where m is the mass of the weight, ρ is the density of the cast iron.
Since the density of cast iron will be the same for two weights, the volume will be greater for a weight with a larger mass (m1 = 20 kg).
The ratio of the volumes of the given weights is equal to the ratio of their masses:
V1 / V2 = m1 / m2 = 20/5 = 4 times.
Answer: The volume of a cast-iron weight weighing 20 kg is 4 times greater than the volume of a weight weighing 5 kg.