Unanswered course student question posted on Mar 15, 2010

[tgb3]

In case my question posted on Mar 15, 2010 was overlooked:

Hello,

I have a couple of questions regarding the Lab 1 - "Data Sufficiency - Quick Elimination".
In the slide #16 it reads: "Use your easy statement to eliminate either AD or BD" - Why should we eliminate AD or BD? We do that only in case a statement is insufficient. Does being "easy" for the statement guarantee its insufficiency?
The second part of the same slide reads: "If you find that both are easy statements, eliminate AD and B"- Same question here, plus the reason of elimination of the choice B is also unclear.
In addition, according to the instructor’s comment: "You need to implement this strategy ONLY IF there is no or very little info in a question" - Why is that?
Overall, the whole purpose of the technique, as well as the last statement, is confusing.

Please advise.
Thanks very much in advance,
Teymuraz

[mschwrtz]

Hey Teymuraz,

I'll look later at the slide you mention, but I don't want to make you wait any longer for an answer.

No, an easy statement need not be easy to recognize as insufficient; sometime a statement is easily recognized as sufficient.

But I think that the slide you refer to makes a point about cases where the information is obviously insufficient, as when you want the value of an expression involving y, and the statement doesn't even mention y.

This would explain the cautionary note you found puzzling. If the question contains information that lets you express y in terms of x and z, for instance, then an apparently insufficient statement might in fact be sufficient. For instance:

If 2y+z=x, what is y-5?

(1) x-z=18

Here, (1) is sufficient.

[tgb3]

Thank you very much for the thorough response!
I have already figured the second part of the question and do not want you to spend time on it, so please do not bother with looking at the slide.
Thanks again!
TB

[mschwrtz]

Great.