Pipes and Cisterns Practice Test 2 with solutions

Time taken by Pipe A to fill an empty tank = 2 × 7 = 14 hours
Remaining portion filled by both (A and B) together = 1 - $\frac{1}{7}$ = $\frac{6}{7}$ th part
$\frac{6}{7}$ th part is filled by A and B in 6 hours
So, the empty tank can be filled by A and B in $6\times \frac{7}{6}$ = 7 hours
Let time taken by Pipe B alone = x hours
So, $\frac{1}{\mathit{x}}+\frac{1}{14}$ = $\frac{1}{7}$
$\frac{1}{\mathit{x}}$ = $\frac{1}{7}-\frac{1}{14}$ = $\frac{2-1}{14}$ = $\frac{1}{14}$
So, time taken by Pipe B alone to fill the tank = 14 hours.