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Pipes A, B and C fill a tank in 3, 4 and 6 hours. A and B are opened together; after 1 hour C is also opened. How long does the whole tank take?

Class 8Pipes and CisternsDirect and Inverse Proportions

A2 hours
B1 1/3 hours
C1 5/9 hours
D1 1/2 hours

Step-by-Step Solution

After 1 h:

\frac{1}{3} + \frac{1}{4} = \frac{7}{12}

. Left

\frac{5}{12}

at

\frac{4 + 3 + 2}{12} = \frac{9}{12} : \frac{5}{9}

h. Total

1 \frac{5}{9}

hours.

Answer: C) 1 5/9 hours

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