Data Sufficiency

Hi jaspreetsra,

You'll find this DS question easier to deal with if you draw a graph (as a general rule, graphing questions are usually easier to solve if you physically draw them). Try graphing the details described by the prompt step-by step...

Step 1) Graph the points (-3, -3) and (1, -3).

We're asked if point R is EQUIDISTANT from those 2 points.

Fact 1: The X-coordinate of point R is -1.

This means that we're looking for ANYTHING that fits the description (-1, Y).

Step 2) Pick ANY value you want for Y, then graph the point. Then pick another and another. Graph them both. You should notice that you form a straight vertical line and that every point is equidistant from (-3, -3) and (1, - 3).
Fact 1 is SUFFICIENT

Fact 2: Point R lies on the line Y = -3

This means that we're looking for ANYTHING that fits the description (X, -3)

Step 3) Pick ANY value you want for X, then graph the point. You'll find that every point is NOT equidistant EXCEPT for (-1, -3).
Fact 2 is INSUFFICIENT.

Final Answer: A

GMAT assassins aren't born, they're made,
Rich

In the xy coordinate plane, is point R equidistant from points (-3,-3) and (1,-3)?
1) The x coordiante of point R is -1
2) Point R lies on the line y=-3

Target question: Is point R equidistant from points (-3,-3) and (1,-3)?

This question is a great candidate for rephrasing the target question.
Aside: We have a free video with tips on rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100

First sketch the two given points


Notice that the point (-1, -3) is equidistant from the two given points. MORE IMPORTANTLY, every point on the line x = -1 is equidistant from the two given points.


So, we can rephrase the target question . . .
REPHRASED target question: Is point R on the line x = -1?

Statement 1: The x coordinate of point R is -1
If the x-coordinate is -1, then point R is definitely on the line x = -1
Since we can answer the REPHRASED target question with certainty, statement 1 is SUFFICIENT

Statement 2: Point R lies on the line y= -3
This tells us nothing about whether or not point R is on the line x = -1?
Since we cannot answer the REPHRASED target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

Cheers,
Brent