Question

How many cubic metres of earth must be dug to sink a well of depth 7 m and diameter 28 m ? Find the cost of plastering its curved surface at 3.50 per sq. m.



help me to solve it....​

Answer 1

Answer:

Given, Earth has to dug out to make well 2.8 m in diameter and 28 m in height.

Also cost of plastering the inner wall is 4.50 per sq. m

Radius =

2

Diameter

=1.4 m

Well is cylindrical in shape.

So,

Volume of well to be dug out =πr

2

h

⇒V=

7

22

×1.4

2

×28

⇒V=172.48 m

3

To find cost of plastering of we have to first find curved surface area of inner wall.

Curved surface area =2πrh

⇒CSA=2×

7

22

×1.4×28

⇒CSA=246.4 m

2

Cost of plastering = Curved Surface Area× Rate per sq. meter

Cost =246.4×Rs. 4.50

⇒ Cost =Rs.1108.8

Answer 2

Question⤵️⤵️

How many cubic metres of earth must be dug to sink a well of depth 7 m and diameter 28 m ? Find the cost of plastering its curved surface at 3.50 per sq. m..

Answer⤵️⤵️

In Attachment...