A and B work together. A alone can complete the work in 24 days and B alone in 24 days. What percentage of the total daily work is contributed by A? MCQ with Answer and Explanation
A and B can complete a work together in 15 days. They work together for 3 days, then A leaves. If B alone completes the remaining work in 16 days, in how many days can A alone complete the whole work?
Explanation:
Let the total work be 60 units. Combined efficiency of A and B = 60 / 15 = 4 units/day. In 3 days, they complete 3 * 4 = 12 units. Remaining work = 60 - 12 = 48 units. B completes 48 units in 16 days, so B's efficiency = 48 / 16 = 3 units/day. A's efficiency = 4 - 3 = 1 unit/day. Time taken by A alone = 60 / 1 = 60 days.
A can do a piece of work in 14 days and B in 21 days. They begin together but 3 days before the completion of the work, A leaves. The total number of days taken to complete the work is:
Explanation:
Total work = LCM(14, 21) = 42 units. Efficiency of A = 3, B = 2. Let total days be x. A works for (x - 3) days and B works for x days. 3*(x - 3) + 2*x = 42 => 3x - 9 + 2x = 42 => 5x = 51 => x = 51/5 = 10(1/5) days.
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