What Makes Tough Quantitative Questions Tough
Many of the most difficult problems are those that cover multiple content areas at once. For instance, Problem Solving #248 in The Official Guide is a tricky permutations problem disguised within coordinate geometry.
The coordinate geometry concepts are basic; the permutations content isn’t that hard, but recognizing what you’ll have to do is much more challenging.
Frequently, the GMAT will mix and match content in word problems. When the numbers are laid out for you, it may just be a matter of remembering an algebra rule, doing a little mental math, and clicking on the right answer.
When the question is a long paragraph, you have to figure out which numbers are which, and do all of the same things you have to do on the non-word problem equivalent.