DS Ratio question

[JbhB682]

At the beginning of February, the ratio of goats to pigs on a certain farm was 7 to 6. What was the ratio of goats to pigs at the end of February?

(1) During the month of February, the number of goats doubled.
(2) During the month of February, the number of pigs decreased by 50%

OA is C | Source : Veritas


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Hello - this was a question from Veritas but Manhattan prep instructors have responded to this question on another forum so i am hoping it is okay if i could ask a clarification

Link to Manhattan Instructor response to this question ;

https://www.beatthegmat.com/at-the-begi ... tml#815193

[JbhB682]

Reason given for elimination of option D was S1 and S2 "cannot contradict" each other per the link blog post


But i dont see how the two statement contradict each other at all

While I agree S1 is not talking about pigs and S2 is not talking about goats -- both S1 and S2 somehow give us the same ratio

S1-- Given number of goats is doubled, the ratio is now 14 : 6 or 7 : 3
S2 -- Given number of pigs is halved -- the ratio is now 7 : 3

I dont see how S1 and S2 contradict each other at all when i derive the same ratio after working on statement 1 and statement 2

[Sage Pearce-Higgins]

Your thinking is good here. Looking at statement (1) and think 'hey, there's no information about pigs here, so the number of pigs could have changed in multiple ways' is exactly the kind of elimination that I'd recommend.

In her post on BeattheGMAT, Ceilidh referenced the fact that statements cannot contradict each other on DS problems to correct the faulty assumption made by the student that "no information about pigs means that the number of pigs has remained constant". If you interpret a statement in a certain way, and then see that interpretation contradicted by the other statement, then it means that your original interpretation was incorrect. Ceilidh wasn't using this reasoning as a way to eliminate answer choice D.