A lead bullet at 30 °C hits a steel plate at 340 m/s and stops…

Step 1. Energy per kilogram. $\tfrac12 \times (340\ \text{m/s})^2 = 57800\ \text{J/kg}$.

Step 2. Warming to the melting point. $130\ \text{J kg}^{-1}\text{K}^{-1} \times (327\ ^\circ\text{C} - 30\ ^\circ\text{C}) = 38610\ \text{J/kg}$.

Step 3. What is left. $57800\ \text{J/kg} - 38610\ \text{J/kg} = 19190\ \text{J/kg}$, less than the $25000\ \text{J/kg}$ needed to melt all of it.

Step 4. Fraction. $\dfrac{19190\ \text{J/kg}}{25000\ \text{J/kg}} = 0.768$.