Discussion
Pipe A can fill a tank in 15 hours, Pipe B in 20 hours and Pipe C can empty it in 12 hours. If all three are opened together, the tank will be filled in:
Answer: C
Correct answer: 30 hours
Work in tanks per hour, treating the emptying pipe as negative.
\[\frac{1}{15} + \frac{1}{20} - \frac{1}{12}\]
Over a common denominator of 60:
\[\frac{4}{60} + \frac{3}{60} - \frac{5}{60} = \frac{2}{60} = \frac{1}{30}\]
The tank fills at one-thirtieth per hour, so it takes 30 hours. The net rate is positive, which is why it fills at all - had C been faster than A and B combined, the tank would never fill.
No comment is present. Be the first to comment.
Loading…
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