Different Individual Times in a Factory Assignment A, B, and C can do the same assignment in 24, 6, and 12 days respectively. If they all work together from the beginning, in how many days will the assignment be completed?
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A33/7 days
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B43/7 days
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C4 days
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D3 days
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E24/7 days
Answer
Correct Answer: 33/7 days
Explanation
Introduction / Context:We must sum three rates and invert to get total time. These numbers are chosen so the result is a tidy fraction in simplest form, a common testing style.
Given Data / Assumptions:
- A: 24 days ⇒ 1/24.
- B: 6 days ⇒ 1/6.
- C: 12 days ⇒ 1/12.
Concept / Approach:Combined rate r = 1/24 + 1/6 + 1/12. Total time = 1/r.
Step-by-Step Solution:Common denominator 24: r = 1/24 + 4/24 + 2/24 = 7/24.Time = 1 / (7/24) = 24/7 days = 3 3/7 days = 33/7 days.
Verification / Alternative check:Decimal: 24/7 ≈ 3.4286, between B’s 6 and C’s 12 when combined with A’s slower rate.
Why Other Options Are Wrong:43/7, 4, 3, or 24/7 (if misread) don’t match the exact 24/7.
Common Pitfalls:Arithmetic errors in fraction addition or misinterpreting 24/7 as an option separate from 33/7.
Final Answer:33/7 days