Combined Filling and Emptying – Verified PYQ Authority Guide
Combined Filling and Emptying is treated here as a focused concept hub. The aim is to show exactly how this concept appears across verified PYQs, which formulas or relationships recur in the solved corpus, and which nearby concepts deserve revision next. Every factual learning cue below is drawn from the existing verified, published and approved English PYQ corpus or from its Knowledge Graph relationships; the hub does not invent unsupported technical claims.
PYQ evidence snapshot
23 verified PYQs are currently mapped to this Concept hub. The represented years include 2025. Exam coverage currently includes RRB NTPC Under Graduate Level. Subject context includes Quantitative Aptitude. These values come from live mappings and can expand automatically when new verified PYQs are added.
Most useful verified PYQs to solve first
Start with the actual questions rather than memorising a generic note. The links below are ranked from the mapped corpus using repeat history and editorial quality, while the complete explanation stays on the individual question page.
- Pipe X can fill a reservoir in 15 hours and pipe Y can empty it in 20 hours. If both pipes are opened simultaneously and pipe Y is closed after 10 hours,…
RRB NTPC Under Graduate Level · 2025
Use the standard Combined Filling and Emptying method and simplify; the result matches 22.5 hours. - Pipes A and B can fill a tank in 12 hours and 15 hours, respectively. A third pipe C can empty the full tank in 20 hours. If A and B are…
RRB NTPC Under Graduate Level · 2025
Use the standard Combined Filling and Emptying method and simplify; the result matches 9 hours. - Inlet M fills a tank in 24 minutes and Inlet N fills it in 32 minutes. Outlet O drains the tank. When all three operate simultaneously, the tank fills in 32 minutes.…
RRB NTPC Under Graduate Level · 2025
Use the standard Combined Filling and Emptying method and simplify; the result matches 24 minutes. - A spherical tank has a radius of 2 meters. If the tank is filled with water to 80% of its total volume, what is the volume of water in the tank (rounded…
RRB NTPC Under Graduate Level · 2025
Use the standard Combined Filling and Emptying method and simplify; the result matches 27. - A cylindrical water tank has a radius of 7 cm and a height of 10 cm. What is its volume? (Use π = 22/7)
RRB NTPC Under Graduate Level · 2025
Use the standard Combined Filling and Emptying method and simplify; the result matches 1540 cm3. - A cistern is filled by two taps, C and D, in 54 minutes and 81 minutes, respectively. There is also a drain E at the bottom. If all three are opened simultaneously,…
RRB NTPC Under Graduate Level · 2025
Use the standard Combined Filling and Emptying method and simplify; the result matches 46.29. - A water pipe is in the shape of a hollow cylinder with an outer radius of 10 cm and an inner radius of 8 cm. If the length of the pipe is…
RRB NTPC Under Graduate Level · 2025
Use the standard Combined Filling and Emptying method and simplify; the result matches 22855 cm2. - A spherical tank has a diameter of 28 cm. What is the total surface area of the tank? (Use π = 22/7)
RRB NTPC Under Graduate Level · 2025
Use the standard Combined Filling and Emptying method and simplify; the result matches 2464 cm².
Formula & key-relationship bank from verified solutions
Work/Filling rate = 1 ÷ time; net rate = filling rates − emptying rates
Use these as revision triggers and open the linked PYQ before applying a formula numerically; variable definitions and assumptions belong to the exact solved question.
Core ideas repeatedly reinforced by the solved corpus
- Use the standard Combined Filling and Emptying method and simplify; the result matches 22.5 hours.
- Use the standard Combined Filling and Emptying method and simplify; the result matches 9 hours.
- Use the standard Combined Filling and Emptying method and simplify; the result matches 24 minutes.
- Use the standard Combined Filling and Emptying method and simplify; the result matches 27.
- Use the standard Combined Filling and Emptying method and simplify; the result matches 1540 cm3.
Exam tips already validated in SRO solutions
- Identify the Combined Filling and Emptying relationship before calculation and keep units/bases consistent.
Common mistakes to avoid
- Using a shortcut without checking its conditions or using the wrong base/unit.
Topic and concept coverage
Mapped topic labels include Time and Work. The concept trail includes Combined Filling and Emptying. Use these labels as a revision map: move from the broad area to the narrow concept, solve a verified PYQ, inspect the detailed reasoning, and then attempt another question from the same cluster.
Knowledge Graph navigation
Continue with Pipes and Cisterns, Time and Work, Arithmetic, Quantitative Aptitude. These are canonical SRO entity links based on the Knowledge Graph and shared question mappings, not keyword-stuffed tag pages.
How to revise this authority page efficiently
- Solve before reading: answer a mapped PYQ first.
- Read the exact explanation: verify the correct principle, formula, distractor logic and common mistake on that question page.
- Move one level in the graph: use the closest concept/sub-topic/topic link rather than opening unrelated content.
- Reattempt: solve another verified PYQ from this hub and check whether the same error repeats.
Quality scope: this page is automatically maintained from SRO’s verified mapped corpus. It enriches one canonical authority URL instead of generating multiple near-duplicate pages for keyword variants. Manual authority articles are never overwritten by the automated engine.