Question

The cost of canvas required for a conical tent of height $8m$ and diameter of base $12m$ at the rate of $Rs.$ $3.50$ per $m^2$ is:

• A. $Rs.$ $620$
• B. $Rs.$ $600$
• C. $Rs.$ $640$
• D. $Rs.$ $660$

Answer 1

The correct option is D $Rs.$ $660$

Given that conical tent of canvas height is $8m$ and diameter of base is $12m$.

Then, radius of base =$\frac{12}{2}=6m$.

Therefore, area of conical tent =$\pi r\left(\sqrt{r^2+h^2}\right)=\frac{22}{7}\times 6\times \sqrt{(8{)}^2+(6{)}^2}\Rightarrow 60\times \frac{22}{7}c{m}^2$.

If cost of canvas is $3.50$ per sq. $cm$,

then cost of canvas=$60\times \frac{22}{7}\times 3.5=Rs.660$.

Hence, option $D$ is correct.