Question

A can do a work in 12 days and B in 16 days. If they work on it together for 3 days then in how many days the remaining work will be completed by B?

A 9 days Correct Answer Incorrect Answer
B 5 days Correct Answer Incorrect Answer
C 7 days Correct Answer Incorrect Answer
D 4 days Correct Answer Incorrect Answer
E 2 days Correct Answer Incorrect Answer

Solution

Total work = Number of days×1 day’s work (efficiency) Total work = LCM (12, 16) = 48 unit 1 day’s work of A = 48/12 = 4 unit 1 day’s work of B = 48/16 = 3 unit 1 day’s work of (A + B) = 4 + 3 = 7 unit Now, 3 day’s work of (A + B) together = 3× 7 = 21 unit Remaining work = 48 – 21 = 27 Remaining work completed by B = 27/3 = 9 days

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