Pipe A can fill a tani in 4 hours and Pipe B can fill it in 6 hours. If they are opened on alternate opurs ad if pipe A is opene first then in how many hours, the tank shall be full?

A) \( \Large 3\frac{1}{2} \)

B) \( \Large 3\frac{1}{4} \)

C) \( \Large 4\frac{1}{2} \)

D) \( \Large 4\frac{21}{3} \)

Correct answer:
D) \( \Large 4\frac{21}{3} \)

Description for Correct answer:

Part of work done in two hours = \( \Large \frac{1}{4}+\frac{1}{6}=\frac{5}{12} \)

Part of work done in 4 hours = \( \Large 2 \left(\frac{5}{12}\right) = \frac{5}{6} \)

Therefore, required time = \( \Large 4 + \frac{\frac{1}{6}}{\frac{1}{4}} = 4\frac{2}{3} hours \)



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