A spherical water tank has an internal diameter of 10 meters. If the tank is coated with a material that costs ₹5 per square meter, what is the total cost to coat the entire internal surface? (Use π = 3.14)
₹1570
The internal radius is half the diameter: \(r = \frac{10}{2} = 5\) m.
Internal surface area of a sphere: \(4\pi r^2 = 4 \times 3.14 \times 5^2 = 4 \times 3.14 \times 25 = 314\) m2.
Cost at ₹5 per square meter: \(314 \times 5 = 1570\).
Hence, the total cost to coat the internal surface is ₹1570.
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Important Questions from 3-D Mensuration
Find the total surface area of a closed cylinder having a base radius of 70 m and a height of 110 m. [Use π = \(22\over7\)]
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The diameter of the base and slant height of a right circular cone are 30 cm and 113 cm, respectively. Find the volume (in cm³) of the given cone.
(Use $\pi = \frac{22}{7}$)- A cylindrical rod has an curved surface area of $4,900 \text{ cm}^2$. If the length of the rod is 97 cm, then the radius (in cm) of the rod, correct to two places of decimal, is:
Take $\pi = \frac{22}{7}$ - The volume (in $m^3$) of a cube, each of whose edges is 42 m, is:
