Question

A cone of height $7$ cm. and base radius $3$ cm. is carved from a rectangular block of wood of dimensions $10cm.\times 5cm.\times 2$ cm. The percentage of wood wasted is

• A. $34\%$
• B. $46\%$
• C. $54\%$
• D. $66\%$

Answer 1

The correct option is A $34\%$

Volume of cone $=$ $\frac{1}{3}\pi r^{2}h=\frac{1}{3}\times \frac{22}{7}\times 3\times 3\times 7=66{cm}^3$

Volume of block $=$ $lbh=10\times 5\times 2=100{cm}^3$

Volume of wood waste $=$ $100-66$ = 34 ${cm}^3$

% Volume waste $=$ $\frac{34}{100}\times 100=34$%