ceilidh.erickson wrote:

vinni.k wrote: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

I don't know why i am inclined towards D..if nothing is said about pigs in (1) then i think they remain unchanged..similarly (2)

You've answered your own question here! This is a common assumption to make... and the GMAT knows this and will exploit it. We can never assume that any situation will hold steady over time unless we're explicitly told so.

Even if you held this assumption that "no info about pigs = pigs stayed the same" when evaluating statement 1, that should have changed when you read statement 2 and saw that the number of pigs had changed. Remember that statements must be true, so they cannot contradict each other. Sometimes evaluating one statement can point out ow we've misinterpreted the other.

Btw, this assumption about situations holding steady over time will often be tested in CR. Consider this:
Company X's revenue went up by 20% since last year, so they must be making a greater profit.
What is the author assuming? That all other circumstances (namely costs) stayed the same over than time. We can't assume this!