Since the middle term 'tigers' is not distributed even once in the premises, no definite conclusion follows. However, I and II involve only the extreme terms and form a complementary pair. So, either I or II follows.
3. Statements: Some dreams are nights. Some nights are days.
Since both the premises are universal and affirmative, the conclusion must be universal affirmative and should not contain the middle term. So, only I follows.
5. Statements: All film stars are playback singers. All film directors are film stars.
Since both the premises are universal and affirmative, the conclusion must be universal affirmative and should not contain the middle term. So, I follows. II is the converse of the second premise and so it also holds.
6. Statements: Some papers are pens. Angle is a paper.
Since the middle term 'papers' is not distributed even once in the premises, no definite conclusion follows. However, I and II involve only the extreme terms and form a complementary pair. Thus, either I or II follows.
7. Statements: All birds are tall. Some tall are hens.
Since the middle term 'tall' is not distributed even once in the premises, no definite conclusion follows. However, II is the converse of the second premise and so it holds.
8. Statements: Some papers are pens. Some pencils are pens.
Since both premises are particular, no definite conclusion follows. However, I is the converse of second premise, while II is the converse of the first premise. So, both of them hold.
9. Statements: Some men are educated. Educated persons prefer small families.
Since both the premises are universal and one premise is negative, the conclusion must be universal negative and should not contain the middle term. So, only I follows.