What is Y intercept of Line l,
1: The Slope of the line is 3 times its Y Intercept
2: X intercept is -1/3
Answer is E, both statements are not sufficient.but how.
My Understanding is it is possible to find the Y intercept which is coming 0.
Please explain.
Quant DS, Please help
This topic has expert replies
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
When posting questions, please use the spoiler function to hide the correct answer. This will allow others to attempt the question without seeing the final answer.Nirupam04 wrote:What is y-intercept of line L?
1) The slope of the line is 3 times its y-intercept
2) The x-intercept is -1/3
Target question: What is the y-intercept of line L?
IMPORTANT: If the x-intercept is -1/3 (as per statement 2), the slope of the line is guaranteed to be 3 times its y-intercept (as per statement 1).
Here's why.
From statement 2, we know that (-1/3, 0) is one point on the line. Let's let (0, k) be the coordinates of the y-intercept of the line. In other words, let's let the y-intercept equal k.
Using the slope formula, the slope = (k - 0)/(0 - (-1/3)) = k/(1/3) = 3k
So, if the y-intercept is k, the slope must be 3k.
In other words, if we're given statement 2, then statement 1 provides no new information. So, if statement 2 is sufficient, then statement 1 must also be sufficient (since it provides no new info). Likewise, if statement 2 is NOT sufficient, then statement 1 is NOT sufficient. At this point, we know that the answer must be either D (they're both sufficient) or E (neither is sufficient).
So, which is it?
Well, if we examine statement 2 on its own (the x-intercept is -1/3), we can see that we do not have enough information to determine the y-intercept of line L.
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Moreover, since statement 1 provides no additional information, it too is NOT SUFFICIENT.
And the combined statements are NOT SUFFICIENT
Answer = E
Cheers,
Brent