A can do a piece of work in 12 days and B can do the same work in 18 days. They work together for 4 days and then A leaves. How many days will B take to complete the remaining work? MCQ with Answer and Explanation
A can do a piece of work in 12 days and B can do the same work in 18 days. They work together for 4 days and then A leaves. How many days will B take to complete the remaining work?
A. 6 days
B. 5 days
C. 7 days
D. 8 days
Answer: Option D
Solution (By JKSSB Mock Tests)
Total work = LCM(12, 18) = 36 units. Efficiency of A = 3, B = 2. Combined efficiency = 5. In 4 days, work completed = 4 * 5 = 20 units. Remaining work = 36 - 20 = 16 units. Time taken by B to complete the remaining work = 16 / 2 = 8 days.
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?
Explanation:
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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