1.

A man installed an overhead tank on his terrace having a cylindrical shape surmounted by hemisphere. The ratio of radius of hemisphere to the height of cylinder is 1 : 4 . If he wants to paint the outer surface of the tank completely, find the cost of painting it at the rate of Rs. 0.1/m2, given the circumference of the base of hemisphere is 88 m.1. 7292. 6163. 7204. 500

Answer» Correct Answer - Option 2 : 616

Given :

Circumference of base of hemisphere = 88 m

 Radius of hemisphere : height of cylinder = 1 : 4

 Cost of painting = Rs. 2 per meter sq.

Formula Used:

 Area of paint = curved surface area of hemisphere + curved surface area of cylinder

 Cost of painting = total curved surface area × cost of painting

Calculations:

Let the radius of hemisphere and height of cylinder be r and h respectively

⇒ Circumference of base of hemisphere = 2πr = 88 m

⇒ r = 14 m

⇒Height of cylinder =  14 × 4

⇒ h =  56 m

⇒CSA of hemisphere = 2πr2 = 2 π × 14 ×14

⇒CSA of hemisphere = 1232 m2

⇒ CSA of cylinder = 2πrh= 2π × 14× 56

⇒ CSA of cylinder = 4928 m2

⇒ Total curved surface area = (4928 + 1232) m2

 ⇒ Total curved surface area =  6160 m2

⇒Cost of painting = Rs. 6160 × 0.1

⇒ Cost of painting = Rs. 616

∴ The cost of painting is Rs. 616.


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