11 men can complete a work in 21 days. If 15 men work at the same rate, in how many days will the work be completed? MCQ with Answer and Explanation
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Question #1
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A and B can do a piece of work in 12 days, B and C in 15 days, and C and A in 20 days. If A, B and C work together, in how many days will they complete the work?
Correct Answer: Option B
Explanation:
Total work = LCM(12, 15, 20) = 60 units. Efficiency of (A+B) = 5, (B+C) = 4, (C+A) = 3. Sum of efficiencies = 2 * (A+B+C) = 12 => Efficiency of (A+B+C) = 6 units/day. Time taken together = 60 / 6 = 10 days.
Total work = LCM(12, 15, 20) = 60 units. Efficiency of (A+B) = 5, (B+C) = 4, (C+A) = 3. Sum of efficiencies = 2 * (A+B+C) = 12 => Efficiency of (A+B+C) = 6 units/day. Time taken together = 60 / 6 = 10 days.
This question belongs to:
Maths
Time and Work
Question #2
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A can complete a work in 13 days and B can complete the same work in 33 days. If they work together, in how many days will the work be completed?
Correct Answer: Option C
Explanation:
Combined rate = 1/13 + 1/33. Time = 1 ÷ combined rate = 9.33 days.
Combined rate = 1/13 + 1/33. Time = 1 ÷ combined rate = 9.33 days.
This question belongs to:
Maths
Time and Work
Question #3
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A can complete a work in 15 days and B in 26 days. If they work together, the work will be completed in:
Correct Answer: Option A
Explanation:
Combined rate = 1/15 + 1/26. Required time = 9.51 days.
Combined rate = 1/15 + 1/26. Required time = 9.51 days.
This question belongs to:
Maths
Time and Work
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