A, B and C can complete a piece of work in 12, 15 and 20 days respectively. A and B start working together and after 2 days A leaves and C joins B. In how many more days will the work be completed? MCQ with Answer and Explanation
A, B and C can complete a piece of work in 12, 15 and 20 days respectively. A and B start working together and after 2 days A leaves and C joins B. In how many more days will the work be completed?
A. 7 days
B. 5 days
C. 6 days
D. 4 days
Answer: Option C
Solution (By JKSSB Mock Tests)
Total work = LCM(12, 15, 20) = 60 units. Efficiency of A = 5, B = 4, C = 3. In 2 days, A and B complete 2 * (5 + 4) = 18 units. Remaining work = 60 - 18 = 42 units. Now, B and C work together with combined efficiency = 4 + 3 = 7 units/day. Time taken to complete the remaining work = 42 / 7 = 6 days.
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