Logical Reasoning - Logical Deduction - Discussion

Discussion Forum : Logical Deduction - Section 3 (Q.No. 7)
Directions to Solve

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


7.

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

Conclusions:

  1. No boat is train.
  2. No bus is boat.
  3. No train is room.

None follows
Only I and II follow
Only II and III follow
Only I and III follow
All follow
Answer: Option
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.

Discussion:
3 comments Page 1 of 1.

Trishul said:   1 decade ago
III definitely follows and it is based in 2 premises: All trains are buses. No room is bus. But since the middle term here, 'bus', is not even distributed once so no definite conclusion should follow.

So how does this work?

Arvind said:   1 decade ago
There is rule if both the premise are negative then no conclusion follows. But here both the conclusions are negative (II and III) but you still drive I one as answer.

Why can you explain it. ?

Ramesh said:   1 decade ago
I want to know very simply to rectify these formats.

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