UPSC Prelims 2010 Q31: Science & Technology – Logical Reasoning & Puzzles
Six books A, B, C, D, E and F are placed side by side. B, C and E have blue cover and the other
books have red cover. Only D and F are new books and the rest are old. A, C and D are law reports
and others are Gazetters. What book is a new law report with a red colour?
- (a) A
- (b) B
- (c) C
- (d) D
Answer: (d) D
Explanation
A books-arrangement logic puzzle
Six books A, B, C, D, E, F, with given cover-colour, new/old, and type (law report/gazetteer) clues.
| Clue | Deduction |
|---|---|
| Blue cover | B, C, E — so red cover = A, D, F |
| New books | D, F — so old books = A, B, C, E |
| Law reports | A, C, D — so Gazetteers = B, E, F |
| Target | A new book that is a law report AND has a red cover |
Checking the new books (D, F) against law reports (A, C, D): only D is both new and a law report. Checking D's colour: D is in the red-cover group (A, D, F). So D satisfies all three conditions.
Cross-checking the attributes:
| Book | Colour | New/Old | Type |
|---|---|---|---|
| D | Red | New | Law report |
| A | Red | Old | Law report |
Answer: (d) D.
Why each option is right or wrong
- (a) Incorrect. A is red and a law report, but it is an old book, not new.
- (b) Incorrect. B is new... actually B is old and a Gazetteer with blue cover, failing all three conditions.
- (c) Incorrect. C is a law report but has a blue cover and is old, failing two conditions.
- (d) CORRECT. D is simultaneously new, a law report, and red-covered — matching all three required conditions.
Key point
Cross-referencing all three clue sets (colour, new/old, type) shows only book D satisfies 'new + law report + red cover' simultaneously.
Remember
Books puzzle: D is the new, red-covered law report — the only book matching all three conditions.
Common mistakes
- Checking only one or two of the three attribute sets instead of cross-referencing all three together.
- Mixing up which books are old vs new, or law reports vs gazetteers.
- Not systematically listing out each book's full attribute profile before answering.
Exam tip
For multi-attribute matching puzzles, build a quick table of all attributes per item before checking the compound condition.
Sources
- R. S. Aggarwal — A Modern Approach to Verbal and Non-Verbal Reasoning (Puzzle Test)
- Arun Sharma — How to Prepare for Logical Reasoning for the CAT (arrangement and attribute-matching puzzles)