Pipes & Cisterns

Duration: 1 hr 12 min

This video lesson is available to enrolled students.

Return to /learn/RSSB-BASIC-COMPUTER-INSTRUCTOR/paper-1-basic-numeracy/pipe-and-cistern/basic-concepts-formulas-and-terminology/asset-pipes-cisterns-15595 after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About the Course: About the Course
  2. Paper-1 & 2 | Basic Numeracy: अनुपात और समानुपात / Ratio and Proportion, Divisibility Rules, मिश्रण और एलिगेशन / Mixture and Alligation, Permutation and Combination, Logarithm, संख्या पद्धति / Number System, महत्तम समापवर्तक और लघुत्तम समापवर्त्य / HCF and LCM, Sequence and Series (Series), समय, चाल और दूरी / Time, Speed and Distance, प्रतिशत / Percentage, औसत / Average, घन क्षेत्रमिति / Solid Mensuration, Age Problems, Arithmetic, Statistics, Probability, लाभ, हानि और बट्टा / Profit, Loss and Discount, साधारण और चक्रवृद्धि ब्याज / Simple and Compound Interest, Partnership, Speed Mathematics and Basic Mathematics, Algebra, सरलीकरण, घातांक और करणी / Simplification, Indices and Surds, समय और कार्य / Time and Work, Pipe and Cistern, RSSB Specific Videos - Basic Numeracy, समुच्चय, संबंध, फलन और विविक्त गणित / Sets, Relations, Functions and Discrete Mathematics, संख्या पद्धति और संख्या सिद्धांत / Number Systems and Number Theory, निर्देशांक ज्यामिति, सदिश और त्रिविमीय ज्यामिति / Coordinate Geometry, Vectors and 3D Geometry, बहुपद, समीकरण और सम्मिश्र संख्याएँ / Polynomials, Equations and Complex Numbers
  3. Paper-1 & 2 | Data Interpretation: आँकड़ा निर्वचन / Data Interpretation
  4. Paper-1 & 2 | General Mental Ability: Mental Ability, RSSB Specific Videos - Mental Ability
  5. Paper-1 & 2 | Logical Reasoning and Analytical Ability: श्रेणी / Series, कूट लेखन एवं कूट वाचन / Coding-Decoding, Data Sufficiency, अशाब्दिक तर्क / Non-Verbal Reasoning, Syllogisms, बैठक व्यवस्था एवं पहेलियाँ / Seating Arrangement and Puzzles, रक्त संबंध / Blood Relations, दिशा एवं दूरी / Direction and Distance, Analytical Reasoning (Counting Figures Reasoning), गणितीय संक्रियाएँ एवं लुप्त संख्या / Mathematical Operations and Missing Numbers, कैलेंडर एवं घड़ी / Calendar and Clock, Clock, घन, पासा एवं आकृतियों की गिनती / Cubes, Dice and Figure Counting, वेन आरेख, न्याय वाक्य एवं असमानता / Venn Diagrams, Syllogism and Inequalities, सादृश्यता एवं वर्गीकरण / Analogy and Classification, क्रम एवं रैंकिंग / Order and Ranking, कथन आधारित तार्किक विवेचन / Statement-Based Reasoning, Data Arrangement, वर्णमाला एवं संख्या परीक्षण / Alphabet and Number Test, Crypt Arithmetic
  6. Paper-1 & 2 | Decision Making and Problem Solving: आँकड़ों की पर्याप्तता एवं निर्णय क्षमता / Data Sufficiency and Decision Making
  7. Paper-1 | General Science: वैज्ञानिक उपलब्धियाँ और अनुसंधान / Scientific Achievements and Research, Biology, Chemistry, RSSB Specific Videos
  8. Paper-1 | General Awareness: राज्य विशेष सामान्य ज्ञान / State-Specific General Knowledge, समसामयिकी / Current Affairs
  9. Paper - 2 | Digital Logic Systems: Digital Systems & Boolean Basics, Logic Gates & Hardware, Combinational Circuit, Sequential Circuits
  10. Paper-2 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Calculus, Relational Algebra, SQL, NoSQL
  11. Paper-2 | Data Structures & Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Algorithm Analysis, Sorting Algorithms, Intro to Compilers, Hashing
  12. Paper 2 | Data Communication and Network Security: Introduction to CN, Data Communication, Data Link Layer - Ethernet, DLL: Error Control, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Application Layer, Hardware basics, Network Security, Ethical Hacking
  13. Paper-2 | Operating Systems: Introduction to OS, Process Management, Memory Management, File Management, Deadlock
  14. Paper-2 | Computer Organization and Architecture: Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations, Programming the Basic Computer, Number System, Number Representation
  15. Paper 2 | System Analysis and Design: Fundamentals of Systems and Information Systems, Fundamentals of Software Engineering, SDLC and Development Approaches, Software Documentation and Software Requirements Specification (SRS), SDD and Quality Assurance, Security, Risk Management & Maintenance, Software Testing
  16. Paper-2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  17. Paper 2 | OOPS , C++ , JAVA: Language Design, OOPS with C++, Java, .Net Programming, Java Fundamentals
  18. Paper 2 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  19. Emerging Trends and AI: Emerging Tech Trends, कंप्यूटर के मूल सिद्धांत / Computer Fundamentals, व्यापार, विपणन एवं उपभोक्ता संरक्षण / Trade, Marketing and Consumer Protection
  20. Paper-2 | Data Processing (Ms-Office): MS Office Applications, कंप्यूटर सॉफ़्टवेयर / Computer Software, ऑपरेटिंग सिस्टम / Operating System, वर्ड प्रोसेसिंग (MS Word) / Word Processing (MS Word), प्रेज़ेंटेशन (MS PowerPoint) / Presentation Software (MS PowerPoint)
  21. Paper-2 | Internet and Web Technologies: HTML Basics, CSS, XML, JavaScript-Basics, Internet Fundamentals, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, Terms & Abbreviations, Cyber Threats and Malware Attacks, Role of Internet and Web Services, Security in Mobile and Wireless Computing, साइबर सुरक्षा / Cyber Safety and Security, कंप्यूटर नेटवर्क / Computer Networks
  22. Paper 2 | Pedagogy: वृद्धि और विकास / Growth and Development, विकास के सिद्धांत / Theories of Development, Concept of Pedagogy, समावेशी शिक्षा / Inclusive Education, Experiential Pedagogy, आकलन और मूल्यांकन / Assessment and Evaluation, संज्ञानात्मक प्रक्रियाएँ / Cognitive Processes, समाजीकरण और जेंडर / Socialisation and Gender, National Education Policy (NEP) 2020
  23. Live Classes: RSSB Live Sessions
  24. Paper 1 - Full Mock Tests:
  25. Paper 2 - Full Mock Tests:
  26. BCI Previous Year Papers:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a comprehensive lecture on 'Pipes and Cisterns' problems, a common topic in aptitude tests. The instructor, Yash Jain Sir, begins by defining inlet and outlet pipes, explaining that inflow represents positive work while outflow represents negative work. The core concept of efficiency being inversely proportional to time is introduced, followed by the '1 hour work' method. The lecture heavily features the 'LCM Method' as a shortcut to solve problems involving fractional rates by assuming a total capacity. Various scenarios are covered, including multiple filling pipes, multiple emptying pipes, mixed scenarios with leaks, and problems where pipes are closed at different times. Real exam questions from companies like LTI, Cognizant, Wipro, and GATE are used to demonstrate practical application.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a visual of a pipe filling a bowl, transitioning to a schematic diagram labeled 'PIPES & CISTERNS'. The instructor introduces the topic, pointing out 'INLET PIPES' adding water and 'OUTLET PIPES' removing it. The diagram clearly labels the 'CISTERN' and the flow of water, setting the stage for understanding the physical setup of these problems before moving to abstract concepts.

  2. 2:00 – 5:00 02:00-05:00

    The slide 'BASIC CONCEPTS' appears, defining 'Inflow / Inlet Pipe' as water flowing into the tank and 'Leak / Outflow / Outlet Pipe' as water flowing out. The instructor underlines these definitions and explains that outflow is considered 'negative work'. This section establishes the fundamental terminology and the sign convention used in subsequent calculations, crucial for solving mixed scenarios.

  3. 5:00 – 10:00 05:00-10:00

    The concept of efficiency is introduced with the statement 'Efficiency is inversely proportional to Time'. An example is given: Pipe A fills in 10 mins, Pipe B in 20 mins. Since A is faster, it is more efficient. The rule 'If Efficiency Ratio is a:b, then Time Ratio will be b:a' is highlighted on the slide, providing a quick way to compare work rates without detailed calculations.

  4. 10:00 – 15:00 10:00-15:00

    The '1 hour work' method is explained in detail. If Pipe A fills in 'x' hours, the part filled in 1 hour is 1/x. Similarly, if Pipe B empties in 'y' hours, the part emptied in 1 hour is 1/y. The instructor writes these fractions on the board to illustrate the rate of work, showing how to convert time taken into a work rate per unit time.

  5. 15:00 – 20:00 15:00-20:00

    Formulas for combined work are derived for different cases. Case I involves two inflow pipes (A+B), Case II involves one inflow and one outflow (A-B), and Case III involves two outflow pipes. The instructor writes the general formulas for these scenarios on the whiteboard, showing how to combine the individual rates to find the net rate of work for the system.

  6. 20:00 – 25:00 20:00-25:00

    A problem is solved using the LCM method. Pipes A and B fill a tank in 36 and 45 hours. The LCM of 36 and 45 is calculated as 180 litres, representing the total capacity. The rates are calculated as 5 litres/hr and 4 litres/hr respectively. This method avoids fractions and simplifies the arithmetic involved in finding the combined work rate.

  7. 25:00 – 30:00 25:00-30:00

    The instructor solves the previous problem by adding the rates (5+4=9 litres/hr). The total time is calculated as Total Capacity / Combined Rate = 180 / 9 = 20 hours. The formula (xy)/(x+y) is also shown as an alternative method for two pipes filling a tank, reinforcing the connection between the LCM method and standard formulas.

  8. 30:00 – 35:00 30:00-35:00

    A problem involving two pipes emptying a tank is presented. Pipe A empties in 10 hours, Pipe B in 5 hours. The instructor applies the formula for two outflow pipes, which is similar to the filling formula but results in a faster emptying time. This demonstrates that the mathematical structure remains consistent regardless of whether the pipes are filling or emptying.

  9. 35:00 – 40:00 35:00-40:00

    A problem with three pipes filling a tank is solved. Pipes A, B, and C fill in 6, 10, and 12 hours. The LCM is 60 litres. Rates are 10, 6, and 5 litres/hr. The combined rate is 21 litres/hr. The time to fill the tank is calculated as 60/21 = 20/7 hours. The formula for three pipes (xyz)/(xy+yz+zx) is written on the board as a shortcut.

  10. 40:00 – 45:00 40:00-45:00

    A problem with two filling pipes and one emptying pipe is discussed. Pipes fill in 10 and 16 hours, while a third empties in 32 hours. The LCM is 160 litres. Rates are 16, 10, and -5 litres/hr. The instructor emphasizes the importance of assigning negative signs to emptying pipes to correctly calculate the net rate of work.

  11. 45:00 – 50:00 45:00-50:00

    A leak problem is introduced. Tap A fills in 12 hours, but with a leak, it takes 15 hours. The instructor calculates the leak's rate by finding the difference in efficiency between the tap alone and the tap with the leak. This scenario highlights how external factors like leaks affect the overall time taken to complete a task.

  12. 50:00 – 55:00 50:00-55:00

    A GATE 2014 problem is solved. It takes 30 minutes to empty a half tank. The goal is to fill the full tank in 10 minutes while simultaneously pumping water in. The draining rate is calculated first. The instructor breaks down the problem into rates per minute to find the required pumping rate relative to the draining rate.

  13. 55:00 – 60:00 55:00-60:00

    The draining rate is found to be 1/60 of the tank per minute (since half tank in 30 mins means full tank in 60 mins). To fill the full tank in 10 mins, the net rate must be 1/10. The pumping rate is calculated to be 3 times the draining rate. This example shows how to handle problems with simultaneous inflow and outflow.

  14. 60:00 – 65:00 60:00-65:00

    A problem where Pipe B is closed after some time is discussed. Pipes A and B fill in 24 and 32 minutes. The tank is filled in 18 minutes. The instructor sets up the equation 18/24 + p/32 = 1 to find the time 'p' Pipe B was open. This introduces the concept of partial work done by different pipes.

  15. 65:00 – 70:00 65:00-70:00

    The instructor solves the pipe closed problem. Pipe A works for the full 18 minutes, contributing 18/24 of the work. The remaining work is done by Pipe B. The equation 18/24 + p/32 = 1 is solved to find p=8 mins. This demonstrates how to calculate the time a specific pipe needs to work to complete the remaining portion of the task.

  16. 70:00 – 72:11 70:00-72:11

    The video concludes with the final answer to the last problem, reinforcing the method used. The instructor summarizes the key takeaways from the lecture, emphasizing the LCM method and the importance of sign conventions for inflow and outflow. The Knowledge Gate logo appears, marking the end of the session.

The lecture systematically builds understanding from basic definitions to complex problem-solving techniques. It starts by defining inlet and outlet pipes and establishing the relationship between efficiency and time. The '1 hour work' method is introduced as a foundational concept, leading to the derivation of formulas for combined work. The 'LCM Method' is presented as a powerful shortcut to handle fractional rates by assuming a total capacity. Various scenarios are covered, including multiple filling pipes, multiple emptying pipes, mixed scenarios with leaks, and problems where pipes are closed at different times. The instructor uses real exam questions from companies like LTI, Cognizant, Wipro, and GATE to demonstrate practical application. The video emphasizes visualizing the problem, assigning rates, and using algebraic equations to find the solution.

Loading lesson…