Books and magazines — Syllogisms Aptitude Question
Books and magazines: Statements: No book is a magazine. All magazines are printed. Conclusions: I. Answer and worked solution on CodeKairo.
- Topic: Syllogisms
- Section: Logical Reasoning
- Difficulty: Hard
- Time target: 90 seconds
Question
Statements:
- No book is a magazine.
- All magazines are printed.
Conclusions: I. Some printed things are not books. II. No printed thing is a book.
Which conclusion follows?
Options
- Only I
- Only II
- Both
- Neither
Show the answer and the worked solution
Correct answer: A. Only I
Worked solution
- All magazines are printed and no magazine is a book, so those printed items are not books: I follows.
- Books could also be printed, so II is too strong.
Answer: Only I.
The idea
Carry the negative only as far as the premises reach. A 'some are not' conclusion is safe where a universal 'no' is not.
Shortcut. Standard pattern: 'No A is B' + 'All B are C' gives 'Some C are not A' — some printed things (the magazines) are not books.
Common trap. "Both" — stretching 'no book is a magazine' into 'no printed thing is a book'; books themselves may well be printed, so II fails.