A cone of height 8 cm and base radius 4 cm is carved from a rectangular block of wood measuring 8 cm × 6 cm × 4 cm. The percentage of wood wasted is approximately:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 30%
Given that
A cone of height (h) = 8 cm and base radius (r) = 4 cm
A rectangular block of wood measuring 8 cm × 6 cm × 4 cm
Formula used
Volume of a cone = ⅓ 𝜋r2h cubic units
Volume of a rectangular block = L × B × H cubic units
According to the question
The wasted material = Volume of the rectangular block - Volume of the cone
= L × B × H - ⅓ 𝜋r2h
= (8 × 6 × 4) - (1/3) × (22/7) × 42 × 8
= 192 - 134.09 = 57.91
Hence, the percentage of wood wasted is approximately = (57.91/192) × 100 = 30 %