achang60153 wrote:Hi,
New to forum and GMAT test taking.
For DS questions, what's the most efficient way to figure out the problem. Do I really have to work the problem out? Do I read it and find out what info. is needed? For the explanations in the OG 11th edition, the answers are solved..like the word problems, but do I really have time to work it out on the real test.
Thanks,
achang
the first thing you can do is realize that there's an optimal order in which to consider the statements and answer choices, so that you don't have to perform redundant reasoning:
* first, decide which of the two statements looks easier to settle. (remember that time management is key; therefore, if you only wind up having the time to deal with one of the statements, then of course it should be the easier of the two.)
* if you consider statement (1) first, realize that A and D are the answer choices in which that statement is SUFFICIENT, and B, C, E are the answer choices in which that statement is INSUFFICIENT.
therefore,
- if you decide (1) is SUFFICIENT, then eliminate B, C, E and keep A, D.
- then decide whether (2) is SUFFICIENT. if it is, then choose D; if not, then choose A. note that there is no need to think about the two statements together in this case.
- if you decide (1) is INSUFFICIENT, then eliminate A, D and keep B, C, E.
- then decide whether (2) is SUFFICIENT. if it is, then choose B.
- if (2) is INSUFFICIENT, then consider the two statements together. if together they are SUFFICIENT, then choose C; if not, choose E.
* if you consider statement (2) first, then the flowchart is effectively the same as the one above, but with A and B switched.
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now it's time for a brief discussion about what SUFFICIENT means:
SUFFICIENT means that
you have enough information to solve the problem uniquely. note, in particular, the word 'uniquely' here: if the problem asks for the value of some variable or quantity, then you must be able to find ONE value for that variable or quantity. if the problem is a yes/no question, then of course you must be able to answer with definitive 'yes' or definitive 'no'.
you are correct that the OG answer explanations usually solve all the way to the end of the problem. note, however, that this is totally unnecessary: all you need is to
get to a point where you know whether or not there will be a solution. in other words, if you have a rather complicated equation on your hands
but you know that it will only have one solution, then you have SUFFICIENT, and there's no need whatsoever to continue solving the problem.
incidentally, there are NO o.g. or gmatprep problems (of which we are aware) to which the answer is 'definitive no'. therefore, if you mark SUFFICIENT for a yes/no question, i can tell you with reasonable assurance that the answer to the question should be 'definitive yes'.
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that should be a good primer. now go out there and start tackling problems! with unfamiliar protocols like that of the DS problems, it's imperative that you gather as much experience as possible.
good luck.
