UNDERSTANDING DATA SUFFICIENCY??

Question

hey guys,
i'm in the elementary stages of gmat prep and i have a question regarding the logic behind data sufficiency. when it comes to the 2 statements that follow the question, should they always be taken as factual information when it comes to answering the question? or are they sometimes wrong or conflicting with each other? i've sampled a few questions and i'm still trying to improve my grasp on what's being asked and how to tackle them.

i apologize if i sound a bit "uninformed"

thanks in advance!

KarishmaB · Answer

I like to think of DS questions as puzzles where the two statements are two clues. You read the puzzle but are not given enough info to solve it. You read clue 1 and then figure out whether you can solve it. Then, you forget about clue 1 and try using clue 2 alone. If you cannot solve it, using either clue alone, you use both clues together to solve it. Obviously, since both statements (clues) are a part of the same puzzle, they CANNOT conflict.

e.g. this is not a valid question:

What is x?
(1) x - 4 = 0
(2) x^2 = 9
The two statements here are conflicting. Stmnt 1 says that x is 4. Stmnt 2 says that its square is 9 which it is not if x is 4.

This, on the other hand, is valid.
What is x?
(1) x - 3 = 0
(2) x^2 = 9
Stmnt 2 doesn't conflict with stmnt 1.

mattjm1121 · Answer

Great thanks for breaking that down. So to reiterate, the statements always yield some truth relative to answering the question; the job is to analyze whether or not the truth in each statement alone or combined make the question answerable. And you must always analyze both statements, even if the first one alone allows you to solve the question. "x-3=0" is enough to answer "what is x?" but you must still check whether or not statement two can stand alone in answering as well.

Thanks again

Thanks again

KarishmaB · Answer

Perfect!

And yes "...but you must still check whether or not statement two can stand alone in answering as well." is true because option (D) is 'Both statements are independently sufficient to answer the question.". So even if statement 1 alone is sufficient, you must analyze statement 2 alone too.

UNDERSTANDING DATA SUFFICIENCY??

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