A is twice as efficient as B. If they complete a work together in 14 days, how many days will A alone take to complete it? MCQ with Answer and Explanation
A is 50% more efficient than B. C does half of the work done by A and B together in the same time. If C alone can do the work in 30 days, then A, B and C together can do the work in:
Explanation:
Let efficiency of B = 2, then efficiency of A = 3. Combined efficiency of A and B = 5. Efficiency of C = 5 / 2 = 2.5. Total work = Efficiency of C * Time of C = 2.5 * 30 = 75 units. Combined efficiency of A, B and C = 3 + 2 + 2.5 = 7.5 units/day. Time taken together = 75 / 7.5 = 10 days.
A can complete a piece of work in 14 days and B in 21 days. They begin together but A leaves 3 days before the completion of the work. Find the total number of days taken to complete the work.
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, B works for x days. 3(x - 3) + 2x = 42 => 3x - 9 + 2x = 42 => 5x = 51 => x = 51/5 = 10(1/5) days.
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