Question:
A cylinder with base radius of 8 cm and height of 2 cm is melted to form a cone of height 6 cm. The radius of the cone is
(a) 4 cm
(b) 5 cm
(c) 6 cm
(d) 8 cm
Solution:
Volume of cylinder $=\pi r^{2} h=\pi \times(8)^{2} \times 2=128 \pi \mathrm{cm}^{2}$
Let $r$ be the radius of cone
But,
The volume of cone $=$ volume of cylinder
$r=8 \mathrm{~cm}$
Hence, Radius of cone = 8 cm.
Hence, the correct answer is choice (d).
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