A can complete a work in 18 days and B in 16 days. If they work together, the work will be completed in: 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 45 days and 40 days respectively. They began the work together, but A left after some days and B finished the remaining work in 23 days. After how many days did A leave?
Correct Answer: Option B
Explanation:
Total work = LCM(45, 40) = 360 units. Efficiency of A = 8, B = 9. B worked alone for 23 days, so work done = 23 * 9 = 207 units. Remaining work = 360 - 207 = 153 units. This was completed by A and B together. Combined efficiency = 8 + 9 = 17. Time worked together = 153 / 17 = 9 days. Thus, A left after 9 days.
Total work = LCM(45, 40) = 360 units. Efficiency of A = 8, B = 9. B worked alone for 23 days, so work done = 23 * 9 = 207 units. Remaining work = 360 - 207 = 153 units. This was completed by A and B together. Combined efficiency = 8 + 9 = 17. Time worked together = 153 / 17 = 9 days. Thus, A left after 9 days.
This question belongs to:
Maths
Time and Work
Question #2
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A can do a piece of work in 12 days and B in 15 days. They work together for 5 days and then B leaves. The days taken by A to finish the remaining work is:
Correct Answer: Option B
Explanation:
Total work = LCM(12, 15) = 60 units. Efficiency of A = 5, B = 4. In 5 days, work done = 5 * (5 + 4) = 45 units. Remaining work = 60 - 45 = 15 units. Time taken by A to finish remaining work = 15 / 5 = 3 days.
Total work = LCM(12, 15) = 60 units. Efficiency of A = 5, B = 4. In 5 days, work done = 5 * (5 + 4) = 45 units. Remaining work = 60 - 45 = 15 units. Time taken by A to finish remaining work = 15 / 5 = 3 days.
This question belongs to:
Maths
Time and Work
Question #3
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A can complete a work in 13 days and B in 42 days. If both work together, in how many days will the work be completed?
Correct Answer: Option C
Explanation:
Combined rate = 1/13 + 1/42. Time = 9.93 days.
Combined rate = 1/13 + 1/42. Time = 9.93 days.
This question belongs to:
Maths
Time and Work
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