How many spherical bullets of diameter 4 cm can be cast by melting a solid cube of edge 44 cm? (Use π = 22/7 where needed.)
-
A2550
-
B2541
-
C2500
-
D2575
Answer
Correct Answer: 2541
Explanation
Introduction / Context:Volume is conserved in melting/recasting. We divide the cube’s volume by the volume of one sphere (bullet) to get the count. The standard approximation π = 22/7 is commonly used in such problems for an exact integer result.
Given Data / Assumptions:
- Cube edge a = 44 cm → V_cube = a^3.
- Bullet sphere diameter = 4 cm → radius r = 2 cm.
- Use V_sphere = (4/3)πr^3 with π = 22/7.
Concept / Approach:n = V_cube / V_sphere; compute carefully to preserve integer results with π = 22/7.
Step-by-Step Solution:
V_cube = 44^3 = 85184 cm^3V_sphere = (4/3)π * 2^3 = (32/3)π = (32/3)*(22/7) = 704/21n = 85184 ÷ (704/21) = 85184 * (21/704) = 121 * 21 = 2541Verification / Alternative check:Reduce 85184/704 = 121 exactly; integer multiplication by 21 yields 2541.
Why Other Options Are Wrong:Near misses result from rounding π or arithmetic slips; only 2541 is exact with 22/7.
Common Pitfalls:Using π ≈ 3.14 leads to a non-integer; forgetting radius is half the diameter.
Final Answer:2541