GMAT Question of the Day – Problem Solving – Geometry/Coordinate Plane
In the XY plan, line J has a positive slope and an x-intercept of 6. If the area of the triangle formed by line J and the two axis is 18, what is the y-intercept of line J?
A. -6
B. -3
C. 3
D. 6
E. 9
[spoiler]A.[/spoiler]
GMAT Question of the Day Solution
For most Geometry questions it is critical to make a diagram. Be careful: double check that you are making a diagram that reflects the information that you are given. A lot of GMAT success is about the proper interpretation of the information that you are given in the question. Take your time setting up the question. I see a lot of GMAT students who feel that there is so much time pressure that they need to speed up. But trying to move faster can create mistakes that slow you down. Improving your speed is about applying the right process and controlling mistakes rather than actually speeding up how you do things. During tutoring sessions I often find myself encouraging students to slow down.
In this question of the day it’s important to note that line J has a positive slope. This means that the triangle will be in quadrant IV. I’ve seen many people take this question and draw a negative slope with the triangle in quadrant I. Once you’ve drawn the appropriate triangle you can set up the area formula and solve for the height of the triangle. Then realize that the answer must be negative since the triangle is in quadrant IV.
Additional GMAT Coordinate Plane Practice Questions
Here’s a GMAT coordinate plane question that’s a bit harder than the above. It is a DS yes/no question and has a bunch of algebra to analyze. Don’t get caught up in treating everything that has a geometry element as a geometry question!
In the xy-plane, does the line with equation y = 3x + 2 contain the point (r,s)?
And another whopper of a coordinate plane question! Once again: yes/no + a bunch of algebra to look at.