What is the capacity of the furnace if 2 tons of steel taken at the melting temperature

What is the capacity of the furnace if 2 tons of steel taken at the melting temperature (1400C) melt for 50 minutes? Furnace efficiency 75%.

Data: m (mass of steel taken) = 2 t (2 * 10 ^ 3 kg); the steel was taken at a melting temperature (1400 ºС); t (melting time) = 50 min (3000 s); η (efficiency of the furnace in which the steel was melted) = 75% (0.75).
Constants: λ (specific heat of melting of steel) = 0.84 * 10 ^ 5 J / kg.
We express the furnace power from the formula: η = N / Np = Q / (Np * t) = λ * m / (Np * t), whence Np = λ * m / (η * t).
Calculation: Np = 0.84 * 10 ^ 5 * 2 * 10 ^ 3 / (0.75 * 3000) = 74 667 W ≈ 75 kW.
Answer: The furnace power is 75 kW.