RRB Group D · Bite-size lessons
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About 7 min · General Intelligence and Reasoning · English
Time worked out from the lesson's 509 words at 150 words a minute, plus a minute for each question.
Direction-based reasoning questions test your ability to visualize movement on a mental compass and calculate final positions or directions. In Railway Group D exams, these problems typically involve a person walking in multiple legs—changing direction at each turn—and you must determine either the shortest distance from the starting point or the final direction they are facing.
Key ideas
- Compass orientation: The standard compass has four cardinal directions—North (top), South (bottom), East (right), West (left)—and four ordinal directions—North-East, South-East, South-West, North-West at 45° angles between cardinals.
- Sign convention for displacement: Treat North and East as positive directions, South and West as negative. Net displacement in North-South axis and East-West axis can be calculated algebraically by summing signed distances.
- Final position calculation: After all movements, calculate net vertical displacement (North minus South) and net horizontal displacement (East minus West). The shortest distance from start to end is the hypotenuse of the right triangle formed by these two net displacements.
- Pythagoras theorem: If net North-South displacement is a units and net East-West displacement is b units, then shortest distance = √(a² + b²).
- Direction turning rules: When facing a direction, "left" is 90° counterclockwise, "right" is 90° clockwise. "About turn" is 180°. Practice mental rotation: if facing North, left = West, right = East, about turn = South.
Watch out for
- Confusing left/right turns with displacement direction: A turn changes facing direction, not the axis of movement. After turning left from North (now facing West), the next movement is westward, not leftward in the previous sense. Fix: Always update "currently facing" before moving.
- Sign errors in North-South or East-West summation: Adding South as positive or forgetting to subtract it from North leads to wrong net displacement. Fix: Stick rigidly to North = +, South = −, East = +, West = −.
- Forgetting to apply Pythagoras: Students sometimes add net North-South and net East-West linearly to get shortest distance (e.g., 3 + 4 = 7 instead of √(3² + 4²) = 5). Fix: Shortest distance is always the hypotenuse, never the sum of legs.
Quick reference
- Shortest distance = √[(Net N-S)² + (Net E-W)²]; always non-negative.
- Net displacement: North − South for vertical; East − West for horizontal.
- Turn rules: Right = clockwise 90°, Left = counterclockwise 90°, About turn = 180°.
- Cardinal opposites: N↔S, E↔W; ordinal opposites: NE↔SW, NW↔SE.
- Pythagorean triples (memorize): 3-4-5, 5-12-13, 8-15-17, 6-8-10 to speed calculation.
Check yourself: 3 questions
1. A man walks 5 km towards North, then turns right and walks 3 km, then again turns right and walks 5 km. In which direction is he from his starting point?
2. Ramesh starts from his house and walks 40 m towards South. Then he turns left and walks 30 m. Again he turns left and walks 40 m. How far is he from his house?
3. A boy walks 3 km towards East, then turns left and walks 4 km, then turns left again and walks 3 km. What is the shortest distance between his starting point and final position?
This lesson is cut from the topic's note, not rewritten. Fact-checked on 21 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.
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