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Question

A can do a work in 10 days and B in 15 days. If they work on it together for 4 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 (10, 15) = 30 unit 1 day’s work of A = 30/10 = 3 unit 1 day’s work of B = 30/15 = 2 unit 1 day’s work of (A + B) = 3 + 2 = 5 unit Now, 4 day’s work of (A + B) together = 4× 5 = 20 unit Remaining work = 30 – 20 = 10 Remaining work completed by B = 10/2 = 5 days

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