Question

A, B and C can complete a work in 10 days, 20 days and 30 days respectively. A and C started the work together and they both work for 6 days. If the remaining work is completed by B and D in 3 days, then find the number of days taken by D to complete (1/5)th of the same work.

A 10 days Correct Answer Incorrect Answer
B 12 days Correct Answer Incorrect Answer
C 14 days Correct Answer Incorrect Answer
D 15 days Correct Answer Incorrect Answer
E None of these Correct Answer Incorrect Answer

Solution

Let the total work (LCM of 10, 20 and 30) = 60 units Efficiency of A = 60/10 = 6 units/day Efficiency of B = 60/20 = 3 units/day Efficiency of C = 60/30 = 2 units/day Work done by A and C together in 6 days = 6 × (6 + 2) = 48 units Remaining work = 60 – 48 = 12 units Efficiency of D = (12/3) – 3 = 1 unit/day Number of days taken by D to complete (1/5)th of the same work = (60/5)/1 = 12 days

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