A can do a piece of work in 20 days and B in 30 days. They work together for some time and then B leaves. If A completes the remaining work in 5 days, for how many days did they work together? MCQ with Answer and Explanation
A can do a piece of work in 20 days and B in 30 days. They work together for some time and then B leaves. If A completes the remaining work in 5 days, for how many days did they work together?
A. 10 days
B. 8 days
C. 6 days
D. 9 days
Answer: Option D
Solution (By JKSSB Mock Tests)
Total work = LCM(20, 30) = 60 units. Efficiency of A = 3, B = 2. A worked alone for 5 days: work done = 5 * 3 = 15 units. Remaining work = 60 - 15 = 45 units. This was completed by A and B together. Combined efficiency = 3 + 2 = 5 units/day. Number of days they worked together = 45 / 5 = 9 days.
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