GMAT Prep - Number Line

rosh26 · Posted: Sat Jun 28, 2008 8:48 pm Post subject: GMAT Prep - Number Line

Thanks in advance.

rey.fernandez · Posted: Sat Jun 28, 2008 10:00 pm Post subject:

A. The solution to this inequality is x<1>1. Eliminate it because it's an unbounded set.

B. The solution to this one is x<=3. Eliminate it because it's an unbounded set.

C. The solution is x<4>4. Again, eliminate because it's an unbounded set.

D. Here, the solution is -5<x<-2 OR 2<x<5. While we have finite (or bounded) sets, unfortunately the question asks for exactly ONE such set, and this inequality has TWO. Eliminate.

E. Simplify:
2<=3x+4<=6
-2<=3x<=2
-2/3<=x<=2/3
This is clearly a single bounded set. The answer is E.

rosh26 · Posted: Sun Jun 29, 2008 3:12 pm Post subject:

Hi, thanks for the response...what is meant by a "bounded" set? unlcear of the actual term...thansl...

rey.fernandez · Posted: Sun Jun 29, 2008 8:22 pm Post subject:

No problem. A bounded set is (roughly) one that has a start and an end. When you graph them on the number line, you get a line segment.
Examples of bounded sets:

-4<x<=7
-3<=x<=0

Unbounded sets are different in that in the positive direction or the negative direction or both directions, the set has no end... it extends out to infinity. When you graph unbounded sets, you get an infinitely long line or ray.
Examples of unbounded sets:
x<4>=7

HTH