Logical Deduction | Logical Reasoning Questions and Answers | Logical Reasoning Free Online-Tests | LucentBlackBoard

Direction to solve :
In each question below are given two statements followed by two conclusions numbered I and II. You have to take the given two statements to be true even if they seem to be at variance from commonly known facts. Read the conclusion and then decide which of the given conclusions logically follows from the two given statements, disregarding commonly known facts.

Give answer:
â€¢ (A) If only conclusion I follows
â€¢ (B) If only conclusion II follows
â€¢ (C) If either I or II follows
â€¢ (D) If neither I nor II follows and
â€¢ (E) If both I and II follow.

01.

Statements: All mangoes are golden in colour. No golden-coloured things are cheap.

Conclusions:
I. All mangoes are cheap.
II. Golden-coloured mangoes are not cheap.

A.	Only conclusion I follows	B.	Only conclusion II follows
C.	Either I or II follows	D.	Neither I nor II follows
E.	Both I and II follow

Answer and Explanation

Answer: Only conclusion II follows

Explanation:
Clearly, the conclusion must be universal negative and should not contain the middle term. So, it follows that 'No mango is cheap'. Since all mangoes are golden in colour, we may substitute 'mangoes' with 'golden-coloured mangoes'. Thus, II follows.

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02.

Statements: All roads are waters. Some waters are boats.

Conclusions:
I. Some boats are roads.
II. All waters are boats.

A.	Only conclusion I follows	B.	Only conclusion II follows
C.	Either I or II follows	D.	Neither I nor II follows
E.	Both I and II follow

Answer and Explanation

Answer: Neither I nor II follows

Explanation:
The first premise is A type and distributes the subject. So, the middle term 'waters' which forms its predicate, is not distributed. The second premise is I type and does not distribute either subject or predicate. So, the middle term 'waters' forming its subject is not distributed. Since the middle term is not distributed even once in the premises, no definite conclusion follows.

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03.

Statements: All aeroplanes are trains. Some trains are chairs.

Conclusions:
I. Some aeroplanes are chairs.
II. Some chairs are aeroplanes.
III. Some chairs are trains.
IV. Some trains are aeroplanes.

A.	None follows	B.	Only I and II follow
C.	Only II and III follow	D.	Only III and IV follow

Answer and Explanation

Answer: Only III and IV follow

Explanation:
Since the middle term 'trains' is not distributed even once in the/premises, no definite conclusion follows. However, III is the converse of the second premise while IV is the converse of the first premise. So, both of them hold.

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04.

Statements: Some bottles are drinks. All drinks are cups.

Conclusions:
I. Some bottles are cups.
II. Some cups are drinks.
III. All drinks are bottles.
IV. All cups are drinks.

A.	Only I and II follow	B.	Only II and III follow
C.	Only II and IV follow	D.	Only III and IV follow
E.	Only I and IV follow

Answer and Explanation

Answer: Only I and II follow

Explanation:
Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, it follows that 'Some bottles are cups'. Thus, I follows. II is the converse of the second premise and so it also holds.

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05.

Statements: Some pictures are frames. Some frames are idols. All idols are curtains.

Conclusions:
I. Some curtains are pictures.
II. Some curtains are frames.
III. Some idols are frames.

A.	Only I and II follow	B.	Only II and III follow
C.	Only I and III follow	D.	All follow
E.	None of these

Answer and Explanation

Answer: Only II and III follow

Explanation:
III is the converse of the second premise and so it holds.
Some pictures are frames. Some frames are idols.
Since both the premises are particular, no definite conclusion follows.
Some frames are idols. All idols are curtains.
Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, it follows that 'Some frames are curtains'. III is the converse of this conclusion and so it holds.
Some pictures are frames. Some frames are curtains.
Since both the premises are particular, no definite conclusion can be drawn.

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06.

Statements: All trains are buses. No room is bus. All boats are rooms.

Conclusions:
I. No boat is train.
II. No bus is boat.
III. No train is room.

A.	None follows	B.	Only I and II follow
C.	Only II and III follow	D.	Only I and III follow
E.	All follow

Answer and Explanation

Answer: All follow

Explanation:
All trains are buses. No room is bus.
Since both the premises are universal and one premise is negative, the conclusion must be universal negative (E-type) and should not contain the middle term. So, it follows that 'No train is room'. Thus, III follows.
All boats are rooms. No room is bus.
As discussed above, it follows that 'No boat is bus'.
II is the converse of this conclusion and so it holds. All trains are buses. No boat is bus.
Again, it follows that 'No train is boat'. I is the converse of this conclusion and so it holds.

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