A, B, C, D can complete a work in 3, 6, 9, 12 hours respectively. Further, <strong>ONLY</strong> one person can work at a time in each hour and nobody can work for two consecutive hours. It is <strong>NOT</strong> necessary to engage all. What is the <strong>MINIMUM</strong> number of hours that they will take to finish the work?
- A. 36/25
- B. 12/5
- C. 4 ✓
- D. 2
Correct Answer: C. 4
Explanation
Let total work be LCM(3,6,9,12) = 36 units. Rates: A=12, B=6, C=4, D=3. To minimize time, alternate the fastest workers, A and B. In 2 hours, they do 12 + 6 = 18 units. In 4 hours, they complete 36 units.
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