In the x-y plane there is a line K, (x/a)+(y/b)=1. What is t

[Max@Math Revolution]

In the x-y plane there is a line K, (x/a)+(y/b)=1. What is the x-intercept of line K?
1) a=2b
2) a=6

*An answer will be posted in 2 days.

[Max@Math Revolution]

We can modify the original condition and the question. When the question asks about the x-intercept, we need to find the value of x when y=0. Then, if we substitute y=0, from x/a=1, we get x=a. Hence, we all need to know the value of a. Since the condition 2) states a=6, the condition is sufficient. Thus, the correct answer is B.



- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

[Brent@GMATPrepNow]

In the x-y plane there is a line K, (x/a)+(y/b)=1. What is the x-intercept of line K?

1) a = 2b
2) a = 6

Target question: What is the x-intercept of line K?

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

Given: the equation of line K is (x/a) + (y/b) = 1.
NOTE: The x-intercept is the x-coordinate of the point where the line intersects the x-axis
IMPORTANT: At this intersection point, the y-coordinate = 0
So, let's plug y = 0 into the equation of line K
We get: (x/a) + (0/b) = 1
Simplify: (x/a) = 1
This means that x = a
In other words, the x-intercept of like K is a
So, we need only find the value of a to answer the target question.

Let's REPHRASE the target question as.....
REPHRASED target question: What is the value of a?

Statement 1: a = 2b
This is not enough info to answer the REPHRASED target question. There are several values of a and b that satisfy statement 1. Here are two:
Case a: a = 4 and b = 2, in which case a = 4
Case b: a = 6 and b = 3, in which case a = 6
Since we cannot answer the REPHRASED target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: a = 6
PERFECT!!
This allows us to answer the REPHRASED target question with certainty. So statement 2 is SUFFICIENT

Answer = B

ASIDE: For more info on finding x and y intercepts, watch this video: https://www.gmatprepnow.com/module/gmat ... /video/996

Cheers,
Brent