4-5. Directions: In each question below are given some statements followed by some conclusions. You have to take the given statements to be true even if they seem to be at variance with commonly known facts. Read all the conclusions and then decide which of the given conclusions logically follows/follow from the given statements, disregarding commonly known facts.

4. Statements:
No apple is a plum.
All plums are oranges.
All oranges are mangoes.

Conclusions:
I. All plums are mangoes.
II. At least some mangoes are oranges.

1. Neither I nor II follows
2. Only I follows
3. Either I or II follows
4. Both I and II follow

EXPLANATION

Answer: D

All plums are oranges (A) + All oranges are mangoes (A) = A + A = All plums are mangoes. Hence, conclusion I follows.

All oranges are mangoes – converse – Some mangoes are oranges. Hence, conclusion II follows.
Hence option D is correct.

5.  Statements:
All animals are mammals.
No mammal is reptile.
All reptiles are amphibians.

Conclusions:
I. All animals are amphibians.
II. Some amphibians are mammals.

1. Neither I nor II follows
2. Only I follows
3. Either I or II follows
4. Both I and II follow

EXPLANATION

Answer: A

Checking  C1: All animals are amphibians.
The class ‘animals’ is in Statement 1 and ‘amphibians’ is in Statement 3 and the link or middle term is available in Statement 2 which is an E type statement. Clearly, using these we can’t have an A type conclusion. C1, clearly, doesn’t follow.
Checking  C2: Some amphibians are mammals.
Applying the same logic, we can’t get a positive conclusion using Statement 2 and Statement 3. C2, doesn’t follow either.
Option A is hence the correct answer.