Question

A tent of 20 mm in radius and 14 mm in height has to be made. If the cost of canvas is Rs. 14 per $m{m}^2$, total cost of canvas used to make the tent is Rs. ____________. ( Use $\pi$ = 22/7)

• A. Rs. 20,400.50
• B. Rs. 21,480.76
• C. Rs. 23,490.56
• D. Rs. 30,000.26

Answer 1

Answer: (B)

Rs. 21,480.76

Radius = 20 mm
Slant height = $\sqrt{r^2+h^2}=\sqrt{{20}^2+{14}^2}$
= $\sqrt{400+196}=24.41mm$
Curved surface area = $\pi rl\Rightarrow \frac{22}{7}\times 20\times 24.41$
= $1,534.34m{m}^2$
$\therefore$ Cost of canvas = $1,534.34\times 14=Rs.21,480.76$