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# GMAT: Data sufficiency 4

16-21, pg. 279. Created by Sal Khan.

## Want to join the conversation?

• At question 21, couldn't you just deduce that 2 is sufficient only by the fact that you can solve the equation by substituion if you know that 6m=9n?
• In question 16,if x>1,7x, that means x<0. And we could get the conclusion.
• That's not what the question is saying. The question says x > 1.7 not x > 1.7x. He writes an x to illustrate that the statement is not sufficient.
(1 vote)
• substitute -1 for x so 9(-1)>10(-1)
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• What type of questions are 16 and 17 and what is the best way to study for them?
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• You know when I think of data sufficiency I think of things like "Is there enough data to calculate the Z score?" or "Is there enough data that the variance is unlikely to be biased?"

However there havent been any of those types of questions yet.

So what is data sufficiency?
(1 vote)
• It is a type of question designed to see whether you can determine whether one, both, or neither of the alternatives would be sufficient (enough) to answer the given question. It rarely requires actually answering the question, as you probably noticed.

There are a lot of questions here where there are comparisons of numbers, positives, negatives, odds, evens, inequalities, and there is a big helping of logic involved as well. If this is true, then is this true? A data sufficiency problem is a kind of number sense problem, and it is an important skill when you work with numbers--especially when you have to draw conclusions from numbers with a lot at stake, such as in business and engineering.
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• IN QUESTION 17 x can be 0. Which is neither ever nor odd? Answer can be E). Or does Gmat considers 0 as even?
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• GMAT considers 0 as even. Every mathematician and math student considers 0 as even.
(1 vote)