\begin{align*} \text{Numerator = } & E[X^4] - 4 \mu E[X^3] + 6 \mu^2 E[X^2] - 3\mu^4\\ & = \left [ 0^4 \cdot 0.10 + 1^4 \cdot 0.25 + 2^4 \cdot 0.40 + 4^4 \cdot 0.15 + 7^4 \cdot 0.10 \right ] - 4 \cdot 2.35 \cdot 47.35 + 6 \cdot 2.35^2 \cdot 9.15^2 - 3 \cdot 2.35^4\\ & \approx 0 + 0.25 + 6.40 + 38.4 + 240.1 - 445.09 + 303.19 - 91.49\\ & \approx 285.15 - 445.09 + 303.19 - 91.49\\ & \approx 51.75 \end{align*}