AMCAT Logical Reasoning: Syllogisms 2

Question 1

All birds can fly. A penguin is a bird. Conclusion: A penguin can fly. This argument is:

Accepted Answer

Valid but unsound

Answer

The argument is logically valid (conclusion follows from premises) but unsound because 'All birds can fly' is factually false.

Question 2

Some students are athletes. All athletes are disciplined. Conclusion: Some students are disciplined.

Accepted Answer

True

Answer

Those students who are athletes are also disciplined → some students are disciplined. True.

Question 3

No reptile is a mammal. A whale is a mammal. Conclusion: A whale is not a reptile.

Accepted Answer

True

Answer

'No reptile is a mammal' is equivalent to 'No mammal is a reptile'. A whale is a mammal → A whale is not a reptile.

Question 4

All M are N. Some N are O. Can we conclude 'Some M are O'?

Accepted Answer

No

Answer

The N's that are O may be entirely different from the N's that are M. We cannot conclude 'Some M are O'.

Question 5

Some A are B. Some B are C. Conclusion: Some A are C.

Accepted Answer

May or may not be true

Answer

The A-B overlap and B-C overlap may be completely disjoint sets of B. No definite conclusion.

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