Question

The radius of a cylindrical vessel is 7 cm and height is 1400 m . Find the cost of painting its inner curved surface area at the rate of 10 DHS per sq cm.(write the units properly)

Answer 1

Cost = 616000 DHS per square centimetre.

Explanation:

curved surface of a cylinder = 2
`\pi`rh

r = 7 cm

h = 1400 m = 140000 cm

The outer curved surface area of the cylinder = inner curved surface area of the cylinder

The inner curved surface of the cylinder = 2
`\pi`rh

= 2 x
`(22)/(7)` x 7 x 140000

= 2 x 22 x 1 x 140000

= 6160000

The inner curved surface of the cylinder is 6160000 square centimetre.

But, the cost of painting is at the rate of 10 DHS per square centimetre.

The inner curved surface of the cylinder = 6.16 x
`10^(6)` square centimetre.

cost of painting the inner curved surface area =
`(6.16*10^(6) )/(10)`

= 616000 DHS per square centimetre

The cost of painting the inner surface is 616000 DHS per square centimetre.