A cylindrical vessel, without lid, has to be tin-coated on its both sides. If the radius of the base is 70 cm
Question:
A cylindrical vessel, without lid, has to be tin-coated on its both sides. If the radius of the base is $70 \mathrm{~cm}$ and its height is $1.4 \mathrm{~m}$, calculate the cost of tin-coating at the rate of Rs $3.50$ per $1000 \mathrm{~cm}$.
Solution:
Given that
Radius of the vessel (r) = 70 cm
Height of the vessel (h) = 1.4 m = 140 cm
The area to be tin coated
$=2 *\left(2 \pi r h+\pi r^{2}\right)$
= 2πr (2h + r)
= 2 * 3.14 * 70[(2 * 140) + 70]
$=154000 \mathrm{~cm}^{2}$
Required cost $=\frac{154000 * 3.5}{1000}=$ Rs 539
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