UPSC Prelims 2001 Q147: Science & Technology – Logical Reasoning & Puzzles
Most guitarists are bearded males. If A represents all males, B represents bearded males
and C represents all male guitarists, then the correct diagram for their relation (shaded portion)
is
- (a) diagram (a)
- (b) diagram (b)
- (c) diagram (c)
- (d) diagram (d)
Answer: (a) diagram (a)
Explanation
Venn diagram for males, bearded males and male guitarists
| Set | Relation (from the statement) |
|---|---|
| A — all males | The largest set |
| B — bearded males | A sub-set of A |
| C — male guitarists | A sub-set of A |
| 'Most guitarists are bearded' | Most of C overlaps B; some of C may lie outside B |
The figure for this question is not available, and no published copy we could find shows it or confirms the answer. The answer below is the key held in our question bank and is not independently verified. From the statement alone, both bearded males (B) and male guitarists (C) lie inside all males (A), and most of C overlaps B. The bank key marks diagram (a).
Answer: (a) diagram (a).
Why each option is right or wrong
- (a) CORRECT. The bank key marks diagram (a).
- (b) Incorrect. The bank key does not mark diagram (b).
- (c) Incorrect. The bank key does not mark diagram (c).
- (d) Incorrect. The bank key does not mark diagram (d).
Key point
'All X are Y' → X inside Y; 'some X are Y' → overlap; 'no X are Y' → separate circles.
Remember
B and C inside A; most of C overlaps B.
Common mistakes
- Drawing guitarists outside the set of males.
- Putting all guitarists inside the bearded set ('most' is not 'all').
- Making bearded males larger than all males.
Exam tip
Translate each word: all = inside, most/some = overlap.
Sources
- NCERT Class XI — Mathematics, chapter 'Sets' (Venn diagrams)
- R. S. Aggarwal — A Modern Approach to Verbal and Non-Verbal Reasoning, chapter 'Logical Venn Diagrams'