Direction sense: Reasoning Ability Notes for BHU Entrance

Direction Sense – Study Notes

(BHU Entrance – Reasoning Ability)

1. Simple Explanation

Direction sense deals with understanding relative positions of objects/people when they are moving or standing.

Absolute directions: North, South, East, West (N, S, E, W).
Relative directions: Front, Back, Left, Right, Rotational sense (clockwise, counter‑clockwise).
Angle notation: 0° (East) → 90° (North) → 180° (West) → 270° (South).

In reasoning problems you are often asked to determine the position of one person relative to another after a series of movements or turns.

2. Key Points to Remember

#	Concept	What to Check	Tips
1	Initial orientation	Who is facing which way?	Use `↓` for South, `↑` for North, `→` for East, `←` for West.
2	Relative movement	“Walks 3 steps to the left” means rotate 90° left from current facing, then move forward.	Keep a mental compass or draw a quick sketch.
3	Rotational moves	‘Turns 90° clockwise’ → direction changes 90° right.	Clockwise = +90°, Counter‑clockwise = –90°.
4	Multiple persons	Track each person separately; if they move together keep their relative orientation unchanged unless stated otherwise.	Label each person (A, B, C) on the sketch.
5	Back and Front	“Back” is opposite of current facing; “Front” is the direction the person is facing.	Useful when a person is told to “stand behind” someone else.
6	Compass vs. Cardinal	Some problems use 8‑point compass (NE, SE, SW, NW).	Remember 45° increments.
7	Reversals	“Turns around” = 180° rotation.	Double‑check if a 180° turn is a reversal or a new heading.
8	Simultaneous actions	If two people move simultaneously, treat them as independent unless the problem says they move together.	Keep separate lines on the sketch.
9	Final position questions	Often ask for who is to the left/right of whom or who is behind whom at the end.	Re‑read the final arrangement carefully.
10	Practice with diagrams	The more you draw, the easier to track.	Even a 2‑line grid works for most problems.

3. Worked Example

Problem

*Six persons A, B, C, D, E, and F stand in a straight line from left to right.

A turns right and walks 2 steps.

B turns left, walks 1 step, and then turns 180°.

C walks 3 steps to the left of B (relative to B’s new direction).

D turns 90° clockwise, walks 1 step, and then turns left.

E turns 90° counter‑clockwise, walks 2 steps, and then turns right.

F turns 180° and walks 1 step.
After all movements, who is standing directly in front of B?*

Step‑by‑Step Solution

Step	Action	Resulting Facing	Movement (steps)	Updated Position
0	Initial	All face East (→)	–	A‑B‑C‑D‑E‑F
1	A turns right (→ becomes South ↓) & walks 2 steps forward (south)	↓	2	A ↓ moves 2 units down
2	B turns left (→ → North ↑) walks 1 step forward (north)	↑	1	B ↑ moves 1 unit up
2b	B turns 180° (now faces South ↓)	↓	–	B remains 1 unit up but facing south
3	C walks 3 steps to the left of B’s new direction (B facing South). Left of South → East (→).	C walks east 3 steps	3	C moves 3 units right
4	D turns 90° clockwise (→ → South ↓) walks 1 step (south)	↓	1	D moves 1 unit down
4b	D turns left (now faces East →)	→	–	D remains 1 unit down
5	E turns 90° counter‑clockwise (→ → North ↑) walks 2 steps (north)	↑	2	E moves 2 units up
5b	E turns right (now faces East →)	→	–	E remains 2 units up
6	F turns 180° (→ → West ←) walks 1 step (west)	←	1	F moves 1 unit left

Visual Sketch (ASCII)

Y
↑
|   (North)
|   A (↓)   (2 steps down)
|   B (↓)   (1 step up, now south)
|   C (→)   (3 steps right)
|   D (←)   (1 step down)
|   E (→)   (2 steps up)
|   F (←)   (1 step left)
+-------------------- X

A: two units below starting line.
B: one unit above starting line, facing south.
C: three units right of starting point, facing east.
D: one unit below starting line, facing east.
E: two units above starting line, facing east.
F: one unit left of starting point, facing west.

Question: Who is standing directly in front of B?
B is facing south (↓). The person standing directly in front (south) of B is **