DS - Quadrant - (bet it is confusing!!!)

[karthikpandian19]

In what quadrant of the coordinate plane does point (w, z) lie, if wz ≠ 0?

(z, w) is in quadrant III.
(-w, z) is in quadrant IV

[sam2304]

1.(z, w) is in quadrant III.

Both z and w are -ve. So (w,z) will also have -ve values and will lie in quad III. SUFF

2.(-w, z) is in quadrant IV

Quad IV has x +ve and y -ve. So -w is +ve and z is -ve => w -ve and z -ve (Quad III). SUFF

IMO D.

[karthikpandian19]

OA is D

[karthikpandian19]

The question asks us to determine which quadrant (w, z) is in, given that neither w nor z is equal to 0. Note that points in quadrant I have positive x and y values, points in quadrant II have negative x values and positive y values, points in quadrant III have negative x and y values, and points in quadrant IV have positive x values and negative y values.

Statement 1 tells us that (z, w) is in quadrant III. As we just observed above, points in quadrant III have negative x values and negative y values, and therefore both w and z are negative and therefore (w, z) is also in quadrant III. Statement 1 alone is sufficient to answer the question. The answer is A or D.

Statement 2 tells us that (-w, z) is in quadrant IV. As we've said, all points in quadrant IV have positive x values and negative y values. This tells us that -w is positive and so w is negative, and that z is negative. Since w and z are both negative, (w, z) is in quadrant III. Statement 2 alone is also sufficient to answer the question.

Answer choice D is correct.

[khandelwal.ab]

Interesting question..thanks for posting Karthik!

[Jim@StratusPrep]

spot on, answer is D. If you know the sign of the numbers, you know the quadrant.