Question
A and B can do a piece of work in 12 days and 18 days,
respectively. They start working together, and after 4 days, A leaves the work. How many more days will B take to complete the remaining work?Solution
Rate of A = 1/12 per day, Rate of B = 1/18 per day. In 4 days, A and B together complete: (1/12 + 1/18) × 4 = (3 + 2) / 36 × 4 = 20 / 36 = 5/9 of the work. Remaining work = 1 - 5/9 = 4/9. B's rate is 1/18 per day. B will take: (4/9) / (1/18) = 4/9 × 18 = 8 days. Correct answer: d. 8 days
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