A cone of height 8 cm and base radius 4 cm is carved from a rectangular block of wood 8 cm × 6 cm × 4 cm. The percentage of wood wasted is approximately:

Correct option is B

Given:
Cone: height (h) = 8 cm, radius (r) = 4 cm
Rectangular block: length = 8 cm, breadth = 6 cm, height = 4 cm
Formula Used:
Volume of a cone = $$\frac13πr^2$$​h,
Volume of a rectangular block = length × breadth × height.
​$$\text{Percentage waste} = \left( \frac{\text{Volume of block} - \text{Volume of cone}}{\text{Volume of block}} \right) \times 100\%$$​​
Solution:
=> Volume of cone = $$\frac 13π(4)^2$$​ × (8) = 134.041 cubic cm
=> Volume of block = 8 × 6 × 4 = 192 cubic cm
=> Waste = 192 - 134.041 = 57.959 cubic cm
=> Percentage waste = $$\frac{57.959}{192}$$​ × 100% ≈ 30%