Two pipes A and B can fill a tank in 18 and 6 h, respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?

A) \( \Large 4\frac{1}2{} \) h

B) 7 h

C) 6 h

D) 10 h

Correct answer:
A) \( \Large 4\frac{1}2{} \) h

Description for Correct answer:

Part filled by A in 1 h = \( \Large 3 \times \frac{1}{18} \)

Part filled by B in 1 h = \( \Large \frac{1}{6} \)

Part filled by (A + B) =

\( \Large \frac{1}{18} \)+\( \Large \frac{1}{6} \) = \( \Large \frac{1+3}{18} \) = \( \Large \frac{4}{18} \) = \( \Large \frac{2}{9} \)

Here, both the pipes together will fill the tank in \( \Large \frac{9}{2} \) h or \( \Large 4\frac{1}{2} \)



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