Question

The diameter of a hollow pipe is 6 cm and it is 14 cm long. What would be the cost of cementing its outer surface if the cost of cementing is ₹ 100 per $c{m}^2$?

• A. ₹ 28,600
• B. ₹ 26,800
• C. ₹ 24,600
• D. ₹ 26,400

Answer 1

The correct option is D ₹ 26,400

Given,
Diameter = 6 cm
$\Rightarrow$ Radius of the pipe, r $=\frac{6}{2}=3cm$

Height, h = 14 cm

Area to be cemented = Curved surface area of the cylinder (hollow pipe) $=2\pi rh$

$=2\times \frac{22}{7}\times 3\times 14$

$=2\times 22\times 3\times 2$

$=44\times 6$

$=264c{m}^2$

Cost of cementing = ₹ 100 per $c{m}^2$

Total cost = 264 x 100 = ₹ 26,400

Therefore, cost of cementing outer surface = ₹ 26,400