Part V — Reasoning & Logical Aptitude

Chapter 6: Reasoning Fundamentals

6.1 Blood Relations

Blood relation puzzles require tracing family relationships through a chain of statements. For example: if A is B's father, and B is C's mother, then A is C's grandfather. Careful diagramming of the family tree, distinguishing generations and gender, is the most reliable solving technique.

6.2 Syllogisms

Syllogisms test logical deduction from given statements using standard categorical forms: "All A are B", "Some A are B", "No A is B", and "Some A are not B". A conclusion is valid only if it necessarily follows from the given statements under all possible interpretations (often best checked using Venn diagrams).

6.3 Coding-Decoding

Coding-decoding questions establish a pattern (e.g., letter shifting, substitution) using a given example, which must then be applied consistently to decode or encode a new word.

6.4 Direction Sense

Direction sense problems track a person's movement in various directions (typically starting facing north) to determine final position or direction relative to the starting point, best solved by plotting movements on a simple coordinate grid.

6.5 Series and Analogy

Number and letter series require identifying the pattern governing a sequence (arithmetic, geometric, or a mixed rule) to find the next term. Analogies test the ability to identify a relationship between a pair of items and apply the same relationship to a new pair.

6.6 Practice Set — Reasoning (16 MCQs)

1. If A is B's father and B is C's mother, then A is C's:
   (a) Uncle (b) Grandfather (c) Brother (d) Cousin
2. Pointing to a photograph, a man says, "She is the daughter of my grandfather's only son." How is the woman related to the man?
   (a) Sister (b) Mother (c) Aunt (d) Daughter
3. In syllogisms, the statement "All A are B" logically means:
   (a) Every member of A is also a member of B (b) No member of A is a member of B (c) Some members of A are B (d) A and B have no relationship
4. Given: "All cats are animals. All animals are living things." Which conclusion necessarily follows?
   (a) All cats are living things (b) All living things are cats (c) No cats are living things (d) Some living things are not cats
5. Given: "Some fruits are red. All red things are sweet." Which conclusion necessarily follows regarding fruits and sweetness?
   (a) Some fruits are sweet (b) All fruits are sweet (c) No fruits are sweet (d) No conclusion can be drawn
6. If in a code, CAT is written as DBU, following a fixed letter-shift rule, how is DOG written?
   (a) EPH (b) EPI (c) FQH (d) CNF
7. A man walks 5 km north, then turns right and walks 3 km, then turns right again and walks 5 km. How far is he from his starting point, and in what direction?
   (a) 3 km, south of start (b) 3 km, east of start (c) 8 km, north of start (d) 3 km, west of start
8. In the series 2, 6, 12, 20, 30, ?, what is the next term (pattern: n×(n+1))?
   (a) 40 (b) 42 (c) 36 (d) 44
9. In the analogy "Pen is to Write as Knife is to ___," the missing word is:
   (a) Sharp (b) Cut (c) Kitchen (d) Metal
10. In the letter series A, C, F, J, O, ?, what is the next letter (gaps increasing by 1: +2,+3,+4,+5,+6)?
    (a) T (b) U (c) S (d) V
11. Data Sufficiency questions primarily test whether:
    (a) The given data is grammatically correct (b) The given data is sufficient to answer a question, without necessarily solving it fully (c) The question has no answer at all (d) Only numerical calculation skill
12. In order and ranking problems, if a student is 7th from the top in a class of 30, their rank from the bottom is:
    (a) 22nd (b) 23rd (c) 24th (d) 21st
13. Seating arrangement puzzles are best solved by:
    (a) Guessing randomly (b) Systematically diagramming clues and eliminating impossible arrangements (c) Ignoring negative clues (d) Solving only the first clue
14. Inequality reasoning questions (e.g., "A > B ≥ C") require candidates to:
    (a) Ignore the relational symbols entirely (b) Combine relational statements logically to determine valid conclusions (c) Assume all variables are equal (d) Only consider the first inequality
15. In a coding pattern where each letter is shifted forward by 2 positions, the letter "Z" would be coded as:
    (a) A (b) B (c) Y (d) X
16. Venn diagrams are a particularly useful tool for solving:
    (a) Only numerical simplification (b) Syllogism-type logical deduction problems (c) Only direction sense problems (d) Only coding-decoding problems

Answer Key

1.(b)

2.(b)

3.(a)

4.(a)

5.(a)

6.(a)

7.(b)

8.(b)

9.(b)

10.(b)

11.(b)

12.(c)

13.(b)

14.(b)

15.(b) 16.(b)