This Bankers Tutorial article is independent educational material. Examples are illustrative, and changing rules or examination requirements should be checked at the official source.
01 / UNDERSTANDING
Understand the idea
A leak changes the rate of progress rather than the tank’s size. Keeping those quantities separate makes the result easy to predict and the calculation straightforward to verify.
02 / UNDERSTANDING
The concept in context
A pipe filling a tank in a stated time contributes the reciprocal of that time as capacity per unit time. An outlet removes capacity and therefore enters with a negative sign. Add compatible rates to obtain the net change, then divide the unfilled capacity by a positive net filling rate when asking for completion time.
If an outlet exceeds the inlet, a tank will not fill from empty under the constant-rate setup. A zero net rate also prevents progress. Staged operation needs a capacity timeline so the remaining fraction is known when a pipe changes state. Real flow can depend on water level, so the aptitude model should state its simplifying assumptions.
03 / UNDERSTANDING
A worked learning case
Original educational case. In an original tank problem, an inlet fills in six hours and an outlet empties a full tank in twelve hours at constant rates. Together the net rate is 1/6 − 1/12 = 1/12 tank per hour. Starting empty, filling takes twelve hours. Adding both rates as positive would wrongly predict faster filling despite the leak.
ORIGINAL EDUCATIONAL PRACTICE
Try it before you check.
Original practice: An inlet fills a tank in 4 hours and a leak empties it in 12 hours. How long to fill from empty with both active at constant rates?
Show the answer and reasoning
6 hours.
The inlet contributes 1/4 tank per hour and the leak removes 1/12. Their net is 3/12 − 1/12 = 2/12 = 1/6 tank per hour. One whole tank therefore takes six hours. The result is slower than the inlet’s four hours alone, a sensible check when an active leak opposes filling.
Two traps to watch for.
- Adding an outlet rate as if it fills the tank.
- Ignoring the capacity already filled before a pipe changes state.
YOUR TOPIC-SPECIFIC LEARNING MAP
Turn understanding into practice
Choose capacity or common work units.
Assign a sign to each rate.
Track remaining capacity after every stage.
Explain the idea, apply it to a new situation, then check what changed in your reasoning.
BANKERS TUTORIAL · SOURCE NOTES
Keep the source alongside your notes.
Official links provide subject context and authoritative reference material. This guide’s explanation, scenario and question are original Bankers Tutorial learning content.
- www.ibps.in https://www.ibps.in/
- www.ibps.in https://www.ibps.in/index.php/faq/
For IBPS & RRB preparation, check the current official notice before relying on changing dates, rules or examination requirements.
