Practice Questions

Duration: 5 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Paper-2 | Programming & Data Structures: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  3. Paper-2 | Databases / DBMS & SQL: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control
  4. Paper-2 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  5. Paper-2 | Computer Networks & Security: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware Basics, Network Access Technologies, Network Security
  6. Paper-2 | Digital Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep
  7. Paper-2 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management
  8. Paper-2 | Theory of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines
  9. Paper-2 | Computer Organization & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer
  10. Paper-2 | Compiler Design: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment
  11. Paper-1 | General Awareness: Polity, Physics, Biology, Chemistry, Static General Knowledge, GK- Current Affairs, History, Geography, Indian Economy, Environment
  12. Paper-1 | Logical Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Data Interpretation, Blood Relations, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Clock, Calendar, Cubes & Dices, Directions (Direction Test), Analogy, Seating Arrangements, Analytical Reasoning (Counting Figures Reasoning)
  13. Paper-1 | Quantitative Aptitude: Ratio and Proportion (Ratios), Mixture and Alligation, Permutation and Combination, Number System, HCF LCM, Speed Time and Distance, Average, Age Problems, Percentage, Profit and Loss, Time and Work, Pipe and Cistern, Simple Interest and Compound Interest, Powers and Exponents (Surds and Indices), Mensuration and Geometry, Probability, Statistics, Arithmetic, Algebra
  14. Paper-1 | English: Vocabulary, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Sentence Construction, Cloze Test (Cloze Passage)
  15. Coal India Previous Year Paper:
  16. Engineering Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Linear Algebra, Calculus
  17. Coal India Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a focused lesson on Group Theory, specifically targeting the identification of groups and the calculation of inverses within modular arithmetic systems. The instructor begins by evaluating four distinct sets and operations to determine which satisfy the axioms of a group. He then proceeds to solve three multiple-choice problems that require applying the definition of an inverse element (a * a^-1 = e) in different modular groups. The lesson emphasizes checking closure, identity, and inverse properties through concrete examples involving addition and multiplication modulo p.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor begins by presenting four mathematical structures labeled 15 through 18, each defining a set and an operation to test for group properties. Structure 15 is {1, ..., p-1} under multiplication. Structure 16 is {0, ..., p-1} under multiplication. Structure 17 is {1, ..., p-1} under addition. Structure 18 is {0, ..., p-1} under addition. The instructor analyzes each to determine if they form a group. He marks 15 as correct because the set of non-zero residues modulo a prime p forms a group under multiplication. He marks 16 as incorrect because the element 0 does not have a multiplicative inverse. He marks 17 as incorrect because the set lacks the identity element 0 for addition. Finally, he marks 18 as correct, as the set of all residues modulo p forms a group under addition.

  2. 2:00 – 5:00 02:00-05:00

    The lecture transitions to solving specific multiple-choice questions involving inverses. The first question asks to identify the false statement for the group {0, 1, 2, 3, 4, 5} under addition modulo 6. The options involve finding inverses. The instructor explains that for an element 'a', its inverse 'a^-1' must satisfy a + a^-1 = 0 (mod 6). He verifies that 1^-1 = 5 (since 1+5=6=0), 2^-1 = 4 (since 2+4=6=0), and 0^-1 = 0. He identifies option (c) 3^-1 = 6 as false because 6 is not in the set and 3+3=0, so the inverse of 3 is 3. The next question involves the group {1, 2, 3, 4, 5, 6} under multiplication modulo 7. He verifies that 1^-1=1, 2^-1=4 (2*4=8=1), 3^-1=5 (3*5=15=1), and 6^-1=6 (6*6=36=1). All options appear true, suggesting a potential trick or error in the question, but he moves on. The final question is about the group {1, 2, 4, 7, 8, 11, 13, 14} under multiplication modulo 15. He checks the inverses: 2^-1=8 (2*8=16=1), 4^-1=4 (4*4=16=1), 7^-1=13 (7*13=91=1). He calculates 11*14=154, which is 4 mod 15, not 1. Thus, he marks option (d) 11^-1 = 14 as the false statement. A Cayley table is displayed for the first problem to visualize the operation.

The video effectively bridges theoretical definitions with practical problem-solving. It starts by reinforcing the conditions for a set to be a group, highlighting common pitfalls like missing identity elements or zero divisors. The progression to specific MCQs demonstrates how to apply these concepts to find inverses. The instructor uses visual aids like checkmarks and crosses to indicate correctness and performs arithmetic calculations on screen to verify modular results, providing a clear, step-by-step method for students to follow when analyzing group properties.

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