Introduction
Verbal and Non-Verbal Reasoning in SSC CGL Tier-I covers a wide range of miscellaneous topics beyond the common series, analogy, and classification. These include direction sense, blood relations, coding-decoding, syllogism, seating arrangement, and non-verbal reasoning like figure series, mirror images, and embedded figures. This topic tests logical thinking, spatial visualization, and analytical skills. The questions are generally straightforward but require careful reading and quick application of rules.
Direction Sense and Blood Relations
Direction sense involves determining the final direction or distance based on given movements. Blood relations require analyzing family relationships and deducing connections. Both are common in SSC CGL and can be solved by drawing diagrams.
Key Points
- Always assume the starting point as origin and use cardinal directions (N, S, E, W).
- For blood relations, use symbols or a family tree to avoid confusion.
- Remember that 'brother of father' is uncle, 'sister of mother' is aunt, etc.
Solved Example 1
Question: A man walks 5 km north, then turns right and walks 3 km, then turns right and walks 5 km. How far is he from the starting point?
Solution: 3 km east
Explanation: Starting at (0,0). After 5 km north: (0,5). Right turn means east: (3,5). Right turn means south: (3,0). Distance from origin = 3 km east.
Solved Example 2
Question: Pointing to a photograph, a man said, 'She is the daughter of my grandfather's only son.' How is the woman related to the man?
Solution: Sister
Explanation: Grandfather's only son = man's father. Daughter of father = man's sister.
Coding-Decoding and Syllogism
Coding-decoding involves deciphering a pattern to encode or decode words/numbers. Syllogism deals with logical conclusions from given statements. These require pattern recognition and logical deduction.
Key Points
- In coding, check letter positions (A=1, B=2, etc.) and common shifts (+1, -1, etc.).
- In syllogism, use Venn diagrams to represent statements and verify conclusions.
- Only conclusions that follow from all possible Venn diagrams are valid.
Solved Example 1
Question: If 'CAT' is coded as 'DBU', how is 'DOG' coded?
Solution: EPH
Explanation: Each letter is shifted by +1: C→D, A→B, T→U. So D→E, O→P, G→H.
Solved Example 2
Question: Statements: All roses are flowers. Some flowers are red. Conclusions: I. Some roses are red. II. All flowers are roses.
Solution: Neither I nor II follows
Explanation: From 'All roses are flowers' and 'Some flowers are red', we cannot conclude that some roses are red (they might not be red). Also, 'All flowers are roses' is not necessarily true.
Non-Verbal Reasoning: Figure Series and Mirror Images
Non-verbal reasoning involves analyzing visual patterns, sequences, and transformations. Figure series require identifying the next figure based on rotation, addition, or deletion of elements. Mirror images require finding the reflection of a figure.
Key Points
- In figure series, track changes in number of lines, shapes, or positions.
- For mirror images, imagine a vertical mirror: left and right are interchanged, top and bottom remain same.
- For water images, top and bottom are interchanged, left and right remain same.
Solved Example 1
Question: A figure shows a dot moving clockwise in a square, one corner per step. After 3 steps from top-left, where is the dot?
Solution: Bottom-right
Explanation: Start top-left. Step 1: top-right. Step 2: bottom-right. Step 3: bottom-left? Wait, clockwise: top-left → top-right → bottom-right → bottom-left. After 3 steps, it is at bottom-left. Correction: After 3 steps from top-left, it is at bottom-left. But if starting at top-left and moving clockwise, positions: 1: top-right, 2: bottom-right, 3: bottom-left. So answer is bottom-left.
Solved Example 2
Question: Which of the following is the mirror image of 'b'?
Solution: d
Explanation: Mirror image of 'b' (vertical mirror) is 'd' because the vertical line remains on the left, but the loop flips to the right.
Practice Questions
Q1. A is B's sister. C is B's mother. D is C's father. E is D's mother. How is A related to D?
Answer: Granddaughter
Explanation: A is sister of B, so A is daughter of C. C is daughter of D. So A is granddaughter of D.
Q2. If 'PEN' is coded as 'QFO', how is 'INK' coded?
Answer: JOL
Explanation: Each letter is shifted by +1: P→Q, E→F, N→O. So I→J, N→O, K→L.
Q3. Statements: All cats are dogs. No dog is a bird. Conclusions: I. No cat is a bird. II. Some dogs are cats.
Answer: Both I and II follow
Explanation: All cats are dogs and no dog is a bird, so no cat is a bird (I follows). Also, all cats are dogs implies some dogs are cats (II follows).
Common Mistakes
- In direction sense, forgetting to account for turns correctly (e.g., right turn from north is east). Always draw a diagram.
- In blood relations, assuming gender based on names or roles without clear indication. Use given relations strictly.
- In syllogism, assuming conclusions that are only possible but not definite. Only definite conclusions follow.
- In mirror images, confusing left-right with top-bottom. Remember mirror reverses left-right, water reverses top-bottom.
Quick Revision
- Direction sense: Use N, S, E, W and draw paths. Right turn = clockwise, left turn = anticlockwise.
- Blood relations: Draw family tree. Use symbols: + for male, - for female, = for marriage, | for offspring.
- Coding-decoding: Check letter positions and shifts. Common patterns: +1, -1, +2, -2, or reverse alphabet.
- Syllogism: Use Venn diagrams. 'All A are B' means A is inside B. 'Some A are B' means overlap.
- Non-verbal: For series, note changes in shape, size, number, rotation. For mirror images, flip horizontally.