A can complete a work in 15 days and B can complete the same work in 15 days. If they work together, in how many days will the work be completed? MCQ with Answer and Explanation
A tank can be filled by pipe A in 6 hours and emptied by pipe B in 8 hours. If both pipes are opened together, how much time will it take to fill the empty tank?
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?
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.
A can do a piece of work in 80 days. He works at it for 10 days and then B alone finishes the remaining work in 42 days. In how many days will A and B together complete the work?
Explanation:
A's 10-day work = 10/80 = 1/8. Remaining work = 7/8. B completes 7/8 work in 42 days, so B completes full work in 42 * (8/7) = 48 days. Combined 1-day work = 1/80 + 1/48 = (3 + 5)/240 = 8/240 = 1/30. They finish together in 30 days.
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