Initial data: V (volume of cast iron core) = 3000 cm ^ 3.
Reference data: ρ (density of cast iron) = 7000 kg / m ^ 3.
SI system: V = 3000 cm ^ 3 = 3000 * 10 ^ -6 m ^ 3 = 3 * 10 ^ -3 m ^ 3.
The mass of a core made of cast iron can be calculated by the formula: m = V * ρ.
Let’s calculate: m = 3 * 10 ^ -3 * 7000 = 21 kg.
Answer: The mass of the cast iron core is 21 kg.
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