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:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 30%.
We know that,
The volume of the cone = 1/3πr2h
where, r = radius and h = height
The volume of block = l × b × h
where l = length, b = breadth and h = height
The volume of the cone = 1/3πr2h
1/3 × 22/7 × 4 × 4 × 8 = 134.09 cm3
The volume of block = l × b × h
8 cm × 6 cm × 4 cm = 192 cm3
Waste wood = 192 - 134.09 = 57.91
Percentage = 57.91/192 × 100 = 5791/192 = 30.16% or 30% approx