Discussion
Pipes A and B can fill a tank in 20 hours and 30 hours, respectively. Pipe C is an emptying pipe. When all the three pipes are opened together, \(\frac{2}{9}\)th part of the tank is filled in 8 hours. Pipe C alone can empty \(\frac{1}{3}\)rd part of the tank in:
Answer: D
Pipe C alone empties one-third of the tank in 6 hours. A and B together fill \(\frac{1}{20} + \frac{1}{30} = \frac{1}{12}\) of the tank per hour. With C also open, \(\frac{2}{9}\) of the tank fills in 8 hours, so the net rate is \[ \frac{2/9}{8} = \frac{1}{36} \] C's emptying rate is \[ \begin{aligned} \frac{1}{12} - \frac{1}{36} &= \frac{2}{36} \\ &= \frac{1}{18} \end{aligned} \] so C empties the whole tank in 18 hours and one-third of it in \(\frac{18}{3} = 6\) hours. The answer 18 hours would be for the whole tank; 3, 4 and 5 hours do not follow from the rate.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development