A storage tank consists of a circular cylinder with a hemisphere stuck on either end. If the external diameter of the cylinder be 1.4 m. and its length be 8 m. find the cost of painting it on the outside at rate of D20 per m2.
The figure is shown below:
Given that, diameter(d) of cylinder is 1.4 m and length(h) is 8 m.
⇒ the radius of sphere(r) = radius of cylinder
⇒ surface area of tank = surface area of cylinder + 2(surface
Area of hemisphere)
= 2πrh + 2(2πr2)
= 2πr(h + 2r)
= 41.36 m2
⇒ ∴ the cost of painting it on the outside at rate of D20 per m2
= 41.36 × 20
= D827.20
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