rajendraputta wrote:- In a question which asks for a value of a quantity, is it possible that the sentences give different but unique value for the quantity asked?

I don't understand your question. Can you pls state it clearly?

rajendraputta wrote:- In a "yes or no" question, is it possible that one sentence gives a "yes" answer and the other a "no" answer?

IMO you will not encounter such statements. However, you may get both yes and no answers for a statement - which means that the statement is insufficient. If you get only 1 answer to a question exactly, then the statement is sufficient.

rajendraputta wrote:- In any question, is it possible that answer given by one of the sentences violates the conditions which might be presented in the second statement?

Never IMO. At least in the official questions. If you encounter such a question, then the source is not authentic and its better to avoid such sources.

@papgust: With reference to my first doubt: Eg: If the question is to find value of x, can 1st statement give answer x=2 and second statement give answer x=4.
What is IMO? Sorry I am new to forum and started preparing for GMAT only last week.

Hi rajendraputta!

Welcome to the community.

Everything the great papgust said is correct.

In any officially released GMAT question, and on the GMAT itself, the two statements will never ever contradict each other.

If statment 1 yields x = 4 and statement 2 yields x = 2, either you did something wrong or else the question is bad.

Of course it is possible that statement 1 yields x = 2 or 4 and statement 2 yields x = 3 or 4. Because the statements can't contradict each other, x, then, must equal 4.

If statement 1 is sufficient because the answer is "always yes", then if statement 2 is also sufficient it will be because the answer is also "always yes".

We can only assume (and should always assume) these two things in DS:

--the statements provide TRUE information
--the statements will never and cannot contradict each other

Thank you Testluv.
That cleared my doubts!