Test Series - logical deduction

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Test Number 2/6

Q: Statements: All roads are poles. No pole is a house.
Conclusions:
I. Some roads are houses.
II. Some houses are poles.
A. Only conclusion I follows
B. Only conclusion II follows
C. Either I or II follows
D. Neither I nor II follows
Solution: Since both the premises are universal and one premise is negative, the conclusion must be universal negative. So, neither I nor II follows.
Q: Statements: All fish are tortoise. No tortoise is a crocodile.
Conclusions:
I. No crocodile is a fish.
II. No fish is a crocodile.
A. Only conclusion I follows
B. Only conclusion II follows
C. Either I or II follows
D. Both I and II follow
Solution: Since both the premises are universal and one premise is negative, the conclusion must be universal negative. Also, the conclusion should not contain the middle term. So, II follows; I is the converse of II and thus it also holds.
Q: Statements: Some swords are sharp. All swords are rusty
Conclusions:
I. Some rusty things are sharp.
II. Some rusty things are not sharp.
A. Only conclusion I follows
B. Only conclusion II follows
C. Either I or II follows
D. Neither I nor II follows
Solution: Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, I follows. Since both the premises are affirmative, the conclusion cannot be negative. Thus, II does not follow.

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