RRB Group D Mock Test 2027: Free CBT Online Test Series
The Railway Recruitment Boards conduct the Level 1 examination with the aim of selecting people to fill posts in track maintenance, points operation, and mechanical assistance in Indian Railways. The exam is one of the largest in the country and as a result hundreds of thousands of candidates apply for the vacancies.
The Computer Based Test (CBT) comprises 100 multiple-choice questions which have to be completed in 90 minutes. Where a candidate gives an incorrect answer, 0.33 marks are deducted in keeping with the standard one-third penalty rule. Candidates must therefore find a balance between speed and accuracy when answering the questions in the areas of General Science, Mathematics, General Intelligence and Reasoning, and General Awareness.
The RRB Group D mock test 2027 modules will help you to build up the stamina that you'll need on the day of the exam. Our practice sets are based on the official bilingual format, allow you to put into practice your knowledge of Class 10 NCERT science, and will prepare you for both the online test and the subsequent Physical Efficiency Test (PET).
Quick Overview: RRB Group D (RRC Level 1) Exam
| Exam Parameter | Details and Official Guidelines |
|---|---|
| Recruitment Authority | Railway Recruitment Control Board (RRCB) / Railway Recruitment Cells (RRCs) |
| Post Classification: | RRC Level 1 (Track Maintainer at Grade IV, Pointsman, Assistant Workshop, etc.) |
| Mode of Examination | Computer Based Test (CBT) followed by Physical Efficiency Test (PET) |
| Total Questions and Marks | 100 questions for 100 marks (1 mark for each correct answer) |
| Test Duration | 90 minutes (120 minutes for eligible PwBD candidates with a scribe) |
| Negative marking | – one-third of a mark is deducted for each incorrect answer. |
| Question Language | Bilingual (English, Hindi, and regional languages as per CEN norms) |
| Final Selection Stages | CBT > Physical Efficiency Test (PET) > Document Verification > Medical Exam |
RRB Group D CBT Exam Pattern and 100-Mark Subject Weightage
The one-stage CBT covers four main areas and has no time limits for the various sections, allowing you to go from one to another during the 90-minute test.
| Subject | Section | Number of Questions | Total Marks | Question Level |
|---|---|---|---|---|
| General Science | 25 questions | 25 marks | Class 10 NCERT (Physics, Chemistry, Life Sciences) | |
| Mathematics | 25 questions | 25 marks | Class 10 Arithmetic, Algebra, Geometry, Mensuration | |
| General Intelligence & Reasoning | 30 questions | 30 marks | Analytical, Verbal, and Non-Verbal Logic | |
| General Awareness & Current Affairs | 20 questions | 20 marks | National Affairs, Railways, Science & Technology, Sports | |
| Total test paper: | 100 questions, 100 marks | 100 Questions | 100 Marks | Composite time: 90 minutes |
General Science (25 questions – Class 10 NCERT Physics, Chemistry & Biology)
One-fourth of the total score is made up of the General Science section. The questions revolve around fundamental scientific principles and the ways in which these can be applied in daily life rather than merely requiring recall. You can anticipate numerical problems in Physics, analyses of chemical reactions in Chemistry, and questions based on diagrams in Biology.
Mathematics (25 questions – Arithmetic, Algebra, Mensuration & Trigonometry)
The mathematics section tests both how fast and how accurately you can carry out calculations. The main arithmetic topics are percentages, ratio and proportion, time and work, and profit and loss. Together with these you will have to deal with basic algebra equations, the formulas for 2D and 3D mensuration, and simple data interpretation charts.
General Intelligence & Reasoning (30 questions – Puzzles, Coding & Analogies)
The reasoning section is the main part of the paper and covers topics such as letter and number sequences, coding and decoding, blood relations, and direction sense. You will also need to work on syllogisms, Venn diagrams, and seating arrangement puzzles, all of which assess your ability to carefully read the rules while under time pressure.
General Awareness & Current Affairs (20 questions – Science, Sports & Culture)
The questions in this section cover your knowledge of recent national events, the policies of Indian Railways, major awards, sporting achievements, and the basic features of Indian polity and geography. They are simple and allow you to answer them rapidly without the need to carry out complicated calculations.
The one-third negative marking rule: avoiding excessive penalty deductions
A deduction of one-third (0.33) of a mark is made for each question answered incorrectly, and there is no penalty for questions that are not attempted.
A number of candidates lower their scores by guessing in a haphazard way. For instance, if you guess at three questions and all three of them are incorrect, then you lose one mark which you would have otherwise obtained.
How penalty deductions affect your net score
Attempts: 92 | Correct: 62 | Wrong: 30
Gross Score: 62.00
Penalty Deduction (30 times 0.333): minus 10.00
Final Net Score: 52.00
Attempts: 76 | Correct: 68 | Wrong: 8
Gross Score: 68.00
Penalty Deduction (8 times 0.333): a deduction of 2.66
The net score at the end was 65.34, a figure that represents an increase of 13.34 marks over the previous score.
Since the mock test interface is able to detect risky attempts, it allows you to practice skipping questions when you can't narrow down your choices.
The Science Decider: Mastering the Class 10 NCERT Numerical Problems
In the RRB Group D exams, General Science is usually the subject that makes the difference. Although a number of examination platforms regard science as just a collection of trivia, the questions in the actual exam require you to apply the formulas from the Class 10 NCERT textbooks.
Breakdown of the Class 10 Science Topics (as in our mock test: 25 questions)
• Electricity & Ohm's Law: 3 Questions
• Optics (Mirrors & Lenses): 3 Questions
• Work, Energy & Motion: 2 Questions
• Chemical Equations & Reactions: 3 Questions
• Periodic Table Trends: 2 Questions
• Acids, Bases, Salts & Metals: 3 Questions
• Life Processes & Human Organ Systems: 4 Questions
• Genetics & Heredity Fundamentals: 2 Questions
• Plant Physiology & Environment: 3 Questions
Physics Formulas: Electricity, Optics, Work and Energy
Many physics questions involve doing calculations. You have to know how to arrange the formulas, substitute the values with the correct units, and be able to work out the final answers quickly:
- Ohm's Law and Resistance: Use the formula V = I × R. When resistors are connected in series, use Rtotal = R1 + R2 + R3. If the resistors are in parallel, find the total resistance from 1 / Rtotal = 1 / R1 + 1 / R2 + 1 / R3.
- Electric Power and Heating: Become familiar with Joule's law of heating (H = I2 × R × t) and the expressions for electric power (P = V × I = I2 × R = V2 / R).
- Spherical Mirrors and Lenses: For both concave and convex mirrors, use the mirror formula 1 / f = 1 / v + 1 / u together with the magnification formula m = -v / u. For lenses, use 1 / f = 1 / v - 1 / u and express the lens power as P = 1 / f (in meters), measured in diopters (D).
- Work, Energy, and Power: Work is given by W = F × s × cos(θ). The formula for kinetic energy is KE = 1/2 m v2, and that for gravitational potential energy is PE = m × g × h.
Chemistry Essentials: Periodic Table Trends and Balancing Reactions
Chemistry questions mainly revolve around chemical reactions and the trends found across the modern periodic table:
- Balancing Chemical Equations: Make sure that the mass is equal on both sides of a chemical reaction. Identify the types of reactions such as displacement, double displacement, combination, and decomposition.
- Periodic Table Trends: As you go from left to right across a period, the atomic radius decreases, while electronegativity and ionization energy increase. When moving down a group, the atomic radius increases, and the metallic character also increases.
- Acids, Bases, and Salts: Remember the common chemical formulas such as baking soda (NaHCO3), washing soda (Na2CO3 · 10H2O), bleaching powder (CaOCl2), and plaster of Paris (CaSO4 · 1/2 H2O).
Life Sciences: Human Physiology, Plant Hormones and Basic Genetics
Biology questions focus on how living organisms function:
- Human Life Processes: Follow the action of digestive enzymes such as pepsin, trypsin, and salivary amylase. Understand how the heart circulates blood through double circulation and how nephrons in the human kidneys filter waste.
- Plant Nutrition and Hormones: Review how xylem carries water and phloem transports food. Remember how plant hormones work: auxins cause cell elongation, gibberellins promote stem growth, cytokinins induce cell division, and abscisic acid suppresses growth.
- Heredity Basics: Know about Gregor Mendel's experiments with pea plants, the monohybrid 3:1 phenotypic ratios, and the XY sex-determination system in humans.
ITI versus 10th Pass: What the Notification Actually States
A frequent question among applicants is whether an Industrial Training Institute (ITI) certificate is needed for Level 1 positions.
According to previous Centralized Employment Notices (CEN), the minimum educational qualification for general entry is:
- a 10th pass (matriculation) from a recognized board, or
- the National Apprenticeship Certificate (NAC) awarded by NCVT, or
- an ITI certificate from institutions recognised by NCVT or SCVT.
Matriculation has in the past been accepted alone for general Level 1 posts, while for technical trades the requirements may include a trade certificate depending on the ministry's guidelines. Always check the educational qualifications listed in the most recent official employment notice before applying.
Why Most RRB Group D Mock Tests Fail Candidates
Many commercial mock test services provide general practice papers that do not match the current railway exams:
- Trivia-Style Science Questions: A number of these platforms use simple recall questions, such as naming the largest bone or organ. In the actual exam, however, questions involve calculations on focal lengths, circuit currents, and balanced chemical equations.
- Poor Translation Quality: A lot of test series depend on automated translations that turn technical physics and chemistry terms into confusing text in Hindi.
- No Preparation for the Physical Stage: Most of these test series concentrate only on the written exam and do not prepare candidates for the Physical Efficiency Test (PET), leaving them unready for the physical demands of stage two.
- Paywalled PDFs and Solutions: Some platforms keep complete answer keys and printable review PDFs behind a paid subscription.
- Unverified Memory-Based Questions: Many websites publish questions submitted by users without verifying whether the numbers and formulas are correct.
Try Our Free RRB Group D Mock Test Series 2027
Use our free online tests, which are organised into full simulation papers, science problem sets, and reasoning drills:
This full simulation has 100 questions matching the official subject distribution of 25-25-30-20. It includes the standard one-third negative marking, an on-screen countdown timer, and a review feature so that you get a real exam experience.
This 23-minute sprint targets the most difficult part of Paper 1. It includes circuit diagrams, ray tracing problems, questions on balancing equations, and diagrams of biological processes.
This 25-minute test helps you solve analytical puzzles more quickly. It concentrates on circular seating arrangements, multi-statement syllogisms, and direction puzzles.
Looking at past exams helps you get a better understanding of how questions are phrased. Download the unofficial memory-based question sets shared by candidates, along with step-by-step solutions, so that you can practice offline.
Test Series Structure and Coverage Matrix
Our 50 practice modules help you build both speed and accuracy step by step before taking full exam simulations.
| Level and Segment | Sections Covered | Number of Tests | Question Format | Focus and Exam Alignment |
|---|---|---|---|---|
| Tier 1: Sectional Drills | Science, Maths, Reasoning, GA | 24 Tests (20 Qs / 18 Min) | Topic-wise timed drills | Speed and accuracy per subject |
| Tier 2: Full-Length CBT | All 4 sections | 16 Tests (100 Qs / 90 Min) | Full simulation with -1/3 penalty | Full-paper stamina, pacing |
| Tier 3: Science Sprint Labs | General Science | 6 Labs (25 Qs / 23 Min) | Formula, circuit, and diagram problems | Application of Class 10 NCERT content |
| Tier 4: PET Readiness | Weight carry + 1000 m run | 4 Printable Guides | Structured training schedules | Qualifying for the physical stage |
Full RRB Group D Syllabus — Micro Breakdown
Use this micro-syllabus checklist to make sure you cover every examinable topic during your preparation:
Comprehensive RRB Group D Syllabus Checklist
General Science
Class 10 StandardKinematics, Newton's Laws, Work-Energy-Power, Gravitation, Pressure, Sound, Ohm's Law, Resistance Networks, Magnetic Effects, Mirror & Lens Formulas
Matter States, Balancing Equations, Types of Reactions, Acids, Bases, pH Scale, Metals & Metallurgy, Carbon Allotropes, Modern Periodic Table
Photosynthesis, Respiration, Human Circulatory & Excretory Systems, Nervous Coordination, Plant Hormones, Cell Division, Heredity Rules
Mathematics
Arithmetic & Advanced MathNumber Systems, BODMAS, Decimals, Fractions, LCM & HCF, Surds & Indices
Percentages, Ratio & Proportion, Profit & Loss, Simple & Compound Interest
Time & Work, Pipes & Cisterns, Speed-Time-Distance, Problems on Trains, Boats & Streams
Elementary Algebra, Polynomials, 2D & 3D Mensuration, Basic Trigonometry, Statistics
General Intelligence & Reasoning
Verbal & Analytical AptitudeAnalogies, Alphabetical & Numerical Series, Coding-Decoding, Mathematical Operations
Blood Relations, Direction Sense, Syllogisms, Venn Diagrams, Jumbling, Data Sufficiency
Seating Arrangements, Ranking, Clock & Calendar, Statement-Arguments, Non-Verbal Logic
General Awareness & Current Affairs
National Affairs & RailwaysNational & International Current Affairs, Science & Technology Developments
Indian Railways History, Zones, Divisions, Budget Highlights & Vande Bharat Milestones
Sports Championships, Indian Polity Basics, Geography, Heritage, Basic Computers
90-Minute Time Management Strategy: Building a Safe Attempt Plan
In a 90-minute CBT you spend about 54 seconds on each question, and as there are no sectional time limits, sticking to a clear order when answering the questions prevents you from running out of time while carrying out long calculations.
The following plan is our recommended approach to help you manage your time effectively:
| Phase Order | Target Section & Question Block | Recommended Time | Focus Strategy |
|---|---|---|---|
| Phase 1 | In the first phase, which is general awareness (20 questions), | you have 10 minutes | — answer the facts that you know immediately and, when you are unsure about a question, do not make any guesses. |
| Phase 2 | In phase 2, which includes 18 questions on general science theory, | you have 15 minutes to complete them | — particularly focusing on solving the conceptual questions in biology, chemistry, and physics quickly. |
| Phase 3 | In Phase 3 the Reasoning Section (30 questions) | lasts for 25 minutes | and you must do the series, the coding and the analogies before turning to the more difficult puzzles. |
| Phase 4 | In Phase 4 there are 25 questions in the Mathematics section | which have to be completed in 25 minutes | by means of the usual shortcuts for arithmetic and algebra. |
| Phase 5 | In Phase 5 there are seven questions on science numericals and puzzles | to be solved in 10 minutes, | the questions involving physics formulas, circuit questions and the other reasoning puzzles. |
| Phase 6 | In Phase 6, at the stage of the Final Review and Error Elimination, | allocate five minutes | to go through the flagged questions and discard the ones for which you are unsure. |
Recommended Time Allocation (Total: 90 Minutes)
Normalization: How Multi-Shift Scores Are Handled
As the RRB Group D examination is held in a number of shifts over a number of weeks, the difficulty of the questions can vary from one session to another.
So that fairness may be guaranteed, the Railway Recruitment Boards apply an official normalization formula when working out the final merit scores, and in earlier recruitment cycles the commission used percentile-based normalization in order to adjust the raw scores across the different shifts.
Raw Score vs Normalized Score Distinction
- The raw score is equal to the sum of the marks received for the questions that were answered correctly minus one-third of a mark for each question.
- The official RRB formula is used to calculate the adjusted score for each shift.
- The platform ranking is a comparative figure for the practices on our website and should not be regarded as an official RRB score.
The unadjusted score displayed on our mock test website together with a simulated percentile rank—this percentile rank being worked out in comparison with all the other people taking the test—allows you to see how you are progressing in relation to other people who are taking the test, but it does not act as a forecast of your official score.
Beyond CBT: Physical Efficiency Test (PET) Standards & Rules
The fact that you have passed the CBT gives you the right to take the Physical Efficiency Test (PET). Yet since this stage is a qualifying one, you will be disqualified right away if you fail any of the events.
The table below outlines the physical standards based on past official employment notices:
| Category of Candidate | Weight Carrying Event (Single Chance, No Dropping) | Endurance Running Event (Single Chance) |
|---|---|---|
| Male candidates | have to carry and lift 35 kg for 100 metres in 2 minutes without putting the weight down | and they also have to run 1000 metres in 4 minutes and 15 seconds. |
| Women candidates | are required to carry and lift 20 kg for a distance of 100 metres in 2 minutes without putting the weight down | and also have to run 1000 metres in 5 minutes and 40 seconds. |
| Individuals who are being considered for PwBD | are generally exempt from the PET in keeping with the old rules; for further information see the latest CEN. | Although they are not required to take part, they are still subject to an assessment by the medical board. |
Practical Training Plan for the PET
Weekly PET Training Schedule
1000m Endurance Running
500m brisk walk and dynamic leg stretching
400m brisk run x 2 rounds with 90-second rests
Run 1000m with a stopwatch, targeting 4m 30s in early weeks
Sandbag Carrying Technique
Bodyweight squats, planks, and lower-back extensions
Practice lifting a 25 kg bag onto your shoulder in one smooth motion
Walk 120m without stopping or adjusting your grip
Begin training for the physical examination several weeks before the results of the written exam are announced since it takes time to build up cardiovascular endurance and to master the carrying technique, and last-minute preparation generally leads to fatigue or injury.
Previous Year Trend Analysis & Subject Distribution
In the most recent cycles of the RRB Group D exams the make-up of the subjects has remained unaltered: 25 per cent General Science, 25 per cent Mathematics, 30 per cent Reasoning, and 20 per cent General Awareness.
Subject Distribution in RRB Group D CBT (Official Pattern)
Practice Score Benchmarks
Rather than trying to guess future cutoffs—which vary widely depending on the railway zone, shift difficulty, and applicant numbers—aim for steady accuracy across all four sections:
| Subject Section | Good Attempt Range | Accuracy Target | Recommended Sectional Raw Score |
|---|---|---|---|
| General Science | 18 to 21 questions | 85% accuracy | 15.00 to 17.50 marks |
| Mathematics | 20 to 22 questions | 90% accuracy | 17.50 to 19.50 marks |
| Reasoning | 25 to 27 questions | 92% correct | 22.50 to 24.50 marks |
| General Awareness | 12 to 14 questions | 80% accuracy | 9.00 to 11.00 marks |
| Total Paper Target | 75 to 84 questions | 88 percent overall accuracy | A net raw score of 64.00 to 72.50 |
Product Features: How Our Analytics Work
The performance metrics available on our practice platform will enable you to identify the areas requiring improvement after each test.
Topic: Series-Parallel Resistance & Ohm's Law
Accuracy Across Last 3 Mocks: 33% (Cohort Average: 76%)
Common Error: Forgetting inverse sum in parallel circuits
Recommended Action: Complete Science Sprint Lab 02
- A system which uses AI will consider your answers from the standpoint of the topic; if you have trouble with optics formulae or with time-and-work problems, your dashboard will display those topics and include a particular practice drill made up of 10 questions.
- You are able to monitor your accuracy by subject, view the average time you take for each question, and use color-coded performance heatmaps to examine your error patterns.
- You can compare your Rank and Percentile Scores with those of other candidates in real time to see how well your preparation is progressing.
- Adaptive Mock Testing: As you improve, our question engine gives you tougher numerical and multi-statement logic problems.
- With each question there is a detailed solution which includes the relevant formulas, shortcut methods, and a reference from the NCERT textbook.
- You can compare the pace that you maintain, the length of time devoted to each topic, and the questions that you choose with those people who have obtained the highest scores.
- Free Daily Current Affairs Practice: Keep up with national news, railway developments, and sports events through our daily quizzes:
Daily Current Affairs & Railway GK Practice
Keep up with national news, railway developments, and sports events through our daily quizzes:
- Keep consistent by setting yourself daily practice goals, keeping a record of your study streaks, and gaining milestone badges as you finish each topic.
Section-wise Preparation Strategy & Essential Study Material
Use reliable reference books that focus on problem-solving rather than passive reading:
| Subject | Recommended Textbook & Edition | Study Strategy |
|---|---|---|
| General Science | For the NCERT Science textbooks in Classes 9 and 10, | go through all the numerical problems, look over each of the chapter summary boxes, and practice balancing reactions. |
| Mathematics | Dr. R.S. Aggarwal's Mathematics Quantitative Aptitude for Competitive Examinations | includes practice in arithmetic shortcuts, mental math calculations, and formulas for 2D and 3D mensuration. |
| Reasoning | A Modern Approach to Verbal & Non-Verbal Reasoning by Dr. R.S. Aggarwal | involves practising seating arrangements, coding puzzles, and direction tests under timed conditions. |
| General Awareness | Lucent General Knowledge and Monthly Current Affairs compilations | Review the fundamentals of Indian polity and geography and take the weekly online current affairs quizzes as part of the compilations. |
Common Mistakes Aspirants Make in RRB Group D Prep
Watch out for these common preparation pitfalls:
- Viewing science as merely a collection of trivial facts, students tend to remember the facts without learning how to solve basic formulas for electrical resistance, focal length, or velocity.
- Trying to guess when there is negative marking causes your total score to drop quickly. Since the penalty is one-third, you must systematically eliminate the answer choices before making an educated guess.
- Pet preparation should be put off until afterwards: with the announcement of the written exam results there will be very little time available to prepare for the 35 kg weight carry and the 1000-meter run.
- Focusing on a single subject—such as concentrating entirely on mathematics or reasoning and ignoring science or general awareness—makes it hard to achieve a competitive score.
- If you take mock tests without checking the mistakes you've made, you'll end up making the same errors over and over again, so it's important to keep an error notebook in which to note down any formulas that you've missed, any calculation mistakes, and any unfamiliar terms.
- When the wording of a technical question is unclear in either Hindi or English, switching to the other language usually makes the problem statement clearer.
High-Yield Sample Practice Questions with Step-by-Step Solutions
These sample questions illustrate the practical, calculation-focused format used across our test series:
Three resistors having resistances of 4 ohms, 6 ohms, and 12 ohms are connected in parallel across a 12 volt battery; what is the total current in the circuit?
(a) 2 A
(b) 4 A
(c) 6 A
(d) 1 A
Correct Answer: (c) 6 A
Step-by-Step Solution:
Calculate the equivalent resistance (Rp) for the parallel combination:
1 / Rp = 1 / 4 + 1 / 6 + 1 / 12
Find the common denominator, which is 12:
1 / Rp = (3 + 2 + 1) / 12 = 6 / 12 = 1 / 2
Therefore, Rp = 2 Ω.
Use Ohm's Law (V = I × R) to find the total current:
I = V / Rp = 12 V / 2 Ω = 6 A
(NCERT Reference: Class 10 Science, Chapter 12: Electricity)
Question: If an object is situated at a distance of 30 cm in front of a convex lens which has a focal length of 20 cm, then at what distance from the lens will the real image be formed?
(a) +60 cm
(b) −60 cm
(c) +40 cm
(d) +15 cm
Correct Answer: (a) +60 cm
Step-by-Step Solution:
Identify given values using standard sign conventions:
Object distance (u) = -30 cm. Focal length (f) = +20 cm (convex lens).
Apply the lens formula:
1 / f = 1 / v − 1 / u
Rearrange to solve for image distance (v):
1 / v = 1 / f + 1 / u = 1 / 20 + (− 1 / 30) = 1 / 20 − 1 / 30
Find the common denominator, which is 60:
1 / v = (3 − 2) / 60 = 1 / 60
Hence, v is plus 60 cm, the positive sign showing that a real and inverted image is formed on the opposite side of the lens.
(NCERT Reference: Class 10 Science, Chapter 10: Light – Reflection and Refraction)
Question: In the chemical reaction aFe + bH2O → cFe3O4 + dH2
What values should the stoichiometric coefficients a, b, c, and d have in order to balance the equation?
(a) a=3, b=4, c=1, d=4
(b) a=2, b=3, c=1, d=3
(c) a=3, b=2, c=1, d=2
(d) a=1, b=4, c=1, d=4
Correct Answer: (a) a=3, b=4, c=1, d=4
Step-by-Step Solution:
Count the atoms of each element on both sides:
Reactants: Fe=a, H=2b, O=b.
Products: Fe=3c, O=4c, H=2d.
Start by balancing the oxygen: set c to 1, then set O to 4, which means that b becomes 4.
Next, balance the iron: since c is 1 and Fe is 3, a must then be 3.
Leave the hydrogen until last: when b is 4, the reactants contain 2 times 4 which is 8 hydrogen atoms. On the product side, 2d equals 8, so d must be 4.
The balanced equation is 3Fe + 4H2O → Fe3O4 + 4H2.
(NCERT Reference: Class 10 Science, Chapter 1: Chemical Reactions and Equations)
How long will it take to fill an empty tank completely if Pipe A and Pipe B are both opened at the same time? Pipe A can fill the tank in 12 hours and Pipe B can do so in 15 hours.
(a) 6 hours 40 minutes
(b) 7 hours 15 minutes
(c) 6 hours 15 minutes
(d) 5 hours 45 minutes
Correct Answer: (a) 6 hours 40 minutes
Step-by-Step Solution:
Let us take the least common multiple of 12 and 15, which is 60 units.
Calculate the hourly rate for each pipe:
Pipe A rate = 60 / 12 = 5 units/hour.
Pipe B rate = 60 / 15 = 4 units/hour.
The total rate when both pipes are open is 5 plus 4, which makes 9 units per hour.
Time taken to fill the tank = 60 / 9 = 20 / 3 hours = 6 2/3 hours.
Convert the fraction to minutes:
2/3 × 60 = 40 minutes.
The total time is 6 hours and 40 minutes.
Five colleagues—P, Q, R, S, and T—are arranged in a straight line with their faces towards the north. R is sitting exactly in the middle of the row. P is at the leftmost end of the row. S is sitting immediately to the right of R. Where is Q sitting if T is sitting between P and R?
(a) Immediate left of R
(b) Extreme right end
(c) Immediate right of P
(d) Between R and S
Correct Answer: (b) Extreme right end
Step-by-Step Solution:
Arrange five positions from left to right: (1, 2, 3, 4, 5).
Put R in the middle; then position 3 will be R.
Put P at the far left. Position 1 is P.
T is situated between P and R: the second position is occupied by T.
S is directly to the right of R: the fourth position is occupied by S.
The one spot without a name is Position 5 and it must therefore be Q's.
Hence Q is at the far right end of the row.
Official Railway Recruitment Portals & Verified Resources
Use these verified official portals and resources to assist your preparation:
| Organization / Resource | Official Website Link | Primary Purpose for Candidates |
|---|---|---|
| Official website of Indian Railways | indianrailways.gov.in | provides information on Railway Board policies, circulars, and recruitment updates. |
| RRB Bhopal (Representative RRB) | rrbbhopal.gov.in | Regional employment advertisements, notices and answer keys |
| SarkariMockTest Railway Hub | sarkarimocktest.com | Free full-length CBT tests, sectional drills, and answer explanations |
Accuracy vs Guesswork: Understanding Expected Value
You will do worse on a test with multiple-choice questions that have negative marking if you guess at random, and this can be understood by considering the expected value calculation.
For a question with four possible answers, the probability of selecting the correct one by guessing is one in four and that of picking the wrong answer is three in four. If the reward is one mark and there is a deduction of one-third of a mark, the expected value is:
Expected Value = (0.25 × 1.0) − (0.75 × 0.333) = 0.25 − 0.25 = 0.00
When you answer a large number of questions by guessing, your expected score will be zero even though there is a risk involved which might lower your score.
However, if you can eliminate just one incorrect option with certainty, the odds shift in your favor:
Expected Value (1 Eliminated) = (1/3 × 1.0) − (2/3 × 0.333) = 0.333 − 0.222 = +0.111
The expected gain then becomes plus 0.333 marks for each attempt if you manage to get rid of two of the options.
You should make only an educated guess when you are certain that at least one of the options can be ruled out.