Question

a hollow cylinder cal pipe has inner circumference 44 DM and Outer 45 cm find the cost of painting it from both side inside as well as outside at rupees 2 per metre square if length is 3.5 metre ​

Answer 1

Solution:-

Inner circumference = 44 dm or 44/10 = 4.4 m

Circumference = 2πr 

4.4 = 2*22/7*r

r = 30.8/44

Inner radius = 0.7 m

Outer circumference = 45 dm or 45/10 = 4.5 m

4.5 = 2*22/7*r

r = 4.5*7/44

r = 31.5/44

Outer radius = 0.716 m

Inner curved surface area = 2πrh

= 2*22/7*0.7*3.5

Inner curved surface area = 15.4 sq m

Outer curved surface area = 2*22/7*0.716*3.5

Outer surface curved area = 15.75 sq m

Total curved surface area =  15.4 + 15.75

= 31.15 sq m

Cost of painting it from both sides (inside and outside) = Rs. 2 per sq m

Total cost of painting = 31.15*2

= Rs. 62.30

Answer.