A cylinder (r = 4 cm, h = 10 cm) is bored through by a hole (r = 2 cm, full height). What percentage of original volume is removed?
25%
Original volume:
\(V_1 = \pi r^2 h = \pi \times 16 \times 10 = 160\pi\)
Volume of removed hole:
\(V_2 = \pi \times 4 \times 10 = 40\pi\)
Percentage removed:
\(\dfrac{40\pi}{160\pi} \times 100 = 25\%\)
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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 = \(22\over7\)]
- The curved surface area of a cylinder is half of its total surface area. If its height is 195 cm, then find its diameter (in cm).
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:
