Question

Pipes A and B can fill a tank in 5 and 6 hours respectively. Pipe C can empty it in 12 hours.
How long will it take to fill the tank, if all the three pipes are opened together?

• A. 30/17 hrs
• B. 30/11 hrs
• C. 60/17 hrs
• D. 9/2 hrs
• E. None of these

Answer 1

The correct option is C

60/17 hrs

Net part filled in 1 hour $=(\frac{1}{5}+\frac{1}{6}-\frac{1}{12})=\frac{17}{60}$

The tank will be full in $\frac{60}{17}hrsi.e.3\frac{9}{17}hrs$