A and B working separately can do a piece of work in 9 and 12 days respectively. If they work for a day alternately, A beginning, in how many days will the work be completed? MCQ with Answer and Explanation
A and B working separately can do a piece of work in 9 and 12 days respectively. If they work for a day alternately, A beginning, in how many days will the work be completed?
A. 10 days
B. 10(1/2) days
C. 10(1/4) days
D. 11 days
Answer: Option C
Solution (By JKSSB Mock Tests)
Total work = LCM(9, 12) = 36 units. Efficiency of A = 4, B = 3. In 2 days (A + B), work done = 4 + 3 = 7 units. In 10 days (5 pairs of 2 days), work done = 7 * 5 = 35 units. Remaining work = 36 - 35 = 1 unit. On the 11th day, it is A's turn. Time taken by A to complete 1 unit = 1/4 day. Total time = 10 + 1/4 = 10(1/4) days.
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