Multiple choice

A solid metallic sphere of radius 10.5 cm is melted and recast into a number of smaller right circular cones of base radius 3.5 cm and height 3 cm each. Find the number of cones formed?

  1. 125

  2. 126

  3. 130

  4. 120
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Volume of sphere = 4/3$\pi$r3 = 4/3$\pi$ (10.5)3 cm3 Volume of cone of base radius 3.5 cm and height 3 cm = 1/3$\pi$ (3.5)2 x 3 cm3 Number of cones formed =$\frac{Volume of sphere}{Volume of cone} \Rightarrow \frac{4/3\pi \times 10.5 \times 10.5}{{1/3\pi}\times 3.5 \times 3.5 \times 3}$     $\Rightarrow$ 126

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