Casting — How many spherical bullets (diameter 2 cm) can be made from a lead cube of edge 22 cm?
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A5324
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B2662
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C1347
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D2541
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E2200
Answer
Correct Answer: 2541
Explanation
Introduction / Context:When recasting, volume is conserved. Number of bullets = (volume of cube) / (volume of one bullet). Use exact π = 22/7 for clean integers here.
Given Data / Assumptions:
- Cube edge a = 22 cm ⇒ V_cube = a^3 = 10648 cm^3
- Bullet diameter = 2 cm ⇒ radius = 1 cm
- Sphere volume V_s = (4/3)πr^3
Concept / Approach:Compute V_s with r = 1 using π = 22/7, then divide the cube volume by V_s and take the integer count.
Step-by-Step Solution:V_s = (4/3) * (22/7) * 1^3 = 88/21 cm^3N = 10648 / (88/21) = (10648 * 21) / 88 = 121 * 21 = 2541
Verification / Alternative check:88 * 121 = 10648, so cancellation is exact.
Why Other Options Are Wrong:2662 and 1347 come from rounding with π = 3.14; 5324 doubles the correct count.
Common Pitfalls:Using diameter instead of radius in sphere volume; forgetting exact fraction 22/7.
Final Answer:2541