ABC26GN5024 · Volume and Surface Area
Subject: General Aptitude · Chapter: Volume and Surface Area · Exam: · Marks: · Difficulty:
How many spherical bullets can be made out of a lead cylinder 15 cm high and with base radius 3 cm, each bullet being 5 mm in diameter?
(a)6000
(b)6480
(c)7260
(d)7800
Answer
Explanation
Volume of cylinder $=\pi \times(3)^{2} \times 15=135 \pi \mathrm{cm}^{3}$. Radius of 1 bullet $=\frac{5}{2} \mathrm{mm}=\frac{5}{20} \mathrm{cm}=\frac{1}{4} \mathrm{cm}$. Volume of 1 bullet $=\left(\frac{4}{3} \pi \times \frac{1}{4} \times \frac{1}{4} \times \frac{1}{4}\right) \mathrm{cm}^{3}=\frac{\pi}{48} \mathrm{cm}^{3}$. $$\text { ∴ Number of bullets }=\left(135 \pi \times \frac{48}{\pi}\right)=6480 .$$
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