Question

A alone can complete 50% of a work in 9 days while B takes 6 days more than A to complete it. If B and C together can complete the work in 12 days, then find the time taken by C alone to complete the same work.

A 30 days Correct Answer Incorrect Answer
B 40 days Correct Answer Incorrect Answer
C 24 days Correct Answer Incorrect Answer
D 42 days Correct Answer Incorrect Answer
E 21 days Correct Answer Incorrect Answer

Solution

Time taken by A alone to complete the entire work = 9/0.5 = 18 days Time taken by B alone to complete the entire work = 18 + 6 = 24 days Let the total work = L.C.M of 18, 24 and 12 = 72 units Then, efficiency of B = (72/24) = 3 units/day Combined efficiency of B and C = (72/12) = 6 units/day So, efficiency of C alone = 6 – 3 = 3 units/day So, time taken by C alone to complete the entire work = (72/3) = 24 days

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