Question

The outer diameter of a pipe is 1 m and it is 21 M long the cost of painting the outer surface of the pipe and the rate of rupees 5 per square metre is

Answer 1

Given :

Outer diameter = 1 m

Height = 21 m

To Find : Cost of painting pipe at the cost of rate of ₹5/m².

Solution :
First of all we have to find it's Curved surface area.

Curved surface area of a cylinder = 2πrh = πdh

$\frac{22}{7} \times 1 \times 21 \\ 22 \times 3 \\ 66$

= 66 m².

Now ,

Cost of painting 1 m² = 5
Cost of painting 66 m² = 5×66 = 330 .

The cost of painting the pipe is ₹330 .

#Be Brainly !!

Answer 2

Solutions :-

We have,

Outer diameter (d) = 1 m
Height (h) = 21 m

Now,

Find the curved surface area of the pipe :-

Curved surface area = (πdh) square units

$= (\frac{22}{7} \times 1 \times 21) {m}^{2} \\ \\ = (22 \times 3) {m}^{2} \\ \\ = 66 \: {m}^{2}$

So, Curved surface area of pipe = 66 m²

Find the cost for painting the outer surface of pipe at the rate of Rs 5/m² :-

1 m² = Rs 5

66 m² = Rs ( 5 × 66) = Rs 330

Answer : Cost of painting the outer surface of pipe = Rs 330