Question

A hollow cylindrical pipe has inner circumference 44 dm and outer 45 dm. Find the cost of painting it
from both sides (inside as well as outside) at 2 per m² if length is 3.5 m.​

Answer 1

Given data :

• A hollow cylindrical pipe has inner circumference 44 dm and outer 45 dm.
• The cost of painting it from both sides (inside as well as outside) at Rs 2 per m² and the length is 3.5 m.

To find : The cost of painting ?

Solution : HERE WE KNOW THAT FORMULA OF CIRCUMFERENCE IS : 2πr

According to given : Inner circumference of hollow cylindrical pipe = 2πr = 44 dm = 4.4 m _____( 1 )

and outer circumference of hollow cylindrical pipe = 2πr = 45 dm = 4.5 m. ______( 2 )

Let, length of hollow cylindrical pipe be height ( h ) of cylindrical pipe.

⟹ h = 3.5 m

Now by formula of curved surface area of cylinder :

⟹ inner C.S.A = 2πr * h

{from ( 1 )}

⟹ inner C.S.A = 4.4 * h

⟹ inner C.S.A = 4.4 * 3.5

⟹ inner C.S.A = 15.4 m²

Similarly,

⟹ outer C.S.A = 2πr * h

{from ( 2 )}

⟹ outer C.S.A = 4.5 * h

⟹ outer C.S.A = 4.5 * 3.5

⟹ outer C.S.A = 15.75 m²

Now,

⟹ cost of painting = 2 * ( inner C.S.A + outer C.S.A )

⟹ cost of painting = 2 * ( 15.4 + 15.75 )

⟹ cost of painting = 2 * 31.15

⟹ cost of painting = Rs 62.3

Answer : Hence cost of painting is Rs 62.3

Learn more :

The dimensions of a cuboidal tin box are 30cm × 40cm × 50cm. Find the tin required for 20 such boxes if the cost of tin ...

https://brainly.in/question/33648853

a verandah under 2.5 metre wide is constructed on the outside of a hall 15 metre long and 10 metre wide find the cost of...

https://brainly.in/question/35093321