Statements : All films are clouds. All rats are clouds. Some clouds are chairs.
Conclusions : (I) No film is chair. (II) Some rats are films.
(III) Some clouds are rats. (IV) Some chairs are rats.
(1) Only I and III follow (2) Either II or IV follows (3) None follows
(4) Only IV follows (5) None of these
Have a confusion over the exact approach
AFAIK The approch is that first check whatever conclusions hold true. Then if a negative conclusion holds true , negate the conslusion once more and check if any conclusion other than the ones that were true before , has underwent any change .
In this case
Conclusion I and III holds true but I is a negative conclusion, negating it we have "Some films are chairs"
Now step1 is see if the premise given before is not violated as in "All films are clouds. All rats are clouds. Some clouds are chairs." still holds true , which is the case here.
And after negating , no other conlusion other than III is getting modified .
So I and III hold true ...
Can some veterean throw light on whether this is the right approach ?