A cylinder (r = 5cm, h = 12cm) is bored by a hole (r = 3cm, full height). Percentage of original volume removed?

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Accepted Answer

1. Compute original cylinder volume: $V_1=\pi r^2 h=\pi(5)^2(12)=300\pi$.  
2. Compute hole volume: $V_2=\pi(3)^2(12)=108\pi$.  
3. Fraction removed = $\dfrac{V_2}{V_1}=\dfrac{108\pi}{300\pi}=\dfrac{108}{300}=0.36$.  
4. Percentage removed = $0.36	imes100\%=36\%$. So the answer is option **(b)**.  
FINAL_ANSWER: b

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