Question

the inner diameter of the circular well is 7m. it is 14m deep find the inner curved surface area and the cost of plastering csa at the rate of 5o ruppes per square m

Answer 1

Given :

• Diameter of circular well = 7 m.

• Depth of circular well = 14 m.

• Cost of Plastering 1 m² area = Rs. 50

To find :

• Inner Curved Surface Area of Well =?

• The cost of plastering the curved surface area of this well =?

Step-by-step explanation :

Diameter of circular well = 7 m. [Given]

Radius of circular well = 7/2 = 3.5 m.

Depth (h) of circular well = 14 m. [Given]

We know that,

Inner Curved Surface Area = 2πrh

Substituting the values in the above formula, we get,

= (2 × 22/7 × 3.5 × 14) m²

= (2 × 22/7 × 35/10 × 14) m²

= 22 × 22 × 35 m²

= 44 × 35 m²

= 1540 m².

Therefore, Inner Curved Surface Area of Well = 1540 m².

Now,

Cost of Plastering 1 m² area = Rs. 50 [Given]

Cost of plastering 1540 m² area, Rs. (1540 × 50) = Rs. 77000

Therefore, the cost of plastering the curved surface area of this well is Rs. 77,000.

Answer 2

$\bigstar$ Given :

• The inner diameter of the circular well is 7 m
• It is 14 m deep
• Cost of plastering is RS. 50 per m²

$\bigstar$ To Find :

• The inner curved surface area
• Cost of plastering curved surface area

$\bigstar$ Solution :

A well resembles cylinder in shape

Inner diameter of well , D = 7 m

⇒ Radius of well , R = 7/2 m

Depth of well , h = 14 m

We know that ,

• " Curved Surface Area of cylinder is 2πrh "

⇒ 2π(7/2)14

⇒ 98π m²

⇒ 1540 m²

Therefore inner curved surface area is 1540 m²

Cost of plastering m² area is RS. 50

Cost of plastering 1540 m² = 1540 * 50

⇒ RS. 77,000

So the cost of plastering curved surface area of 1540 m² is

RS. 77,000