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by [email protected] » Sun Dec 08, 2013 11:50 am
Hi shibsriz,

This DS question asks if a line has a slope of 0. This essentially asks "Is the line horizontal?" This is a YES/NO question.

Fact 1: The X-intercept is 0

This means that the line intercepts the X-axis at the origin (0,0). Unfortunately, we don't know anything else about the line. The slope could be positive (answer is NO), negative (answer is NO) or 0 (answer is YES).
Fact 1 is INSUFFICIENT

Fact 2: The Y-intercept is 0

This also means that the line intercepts the origin (0,0). We still don't know if the slope is positive, negative or 0.
Fact 2 is INSUFFICIENT

Combined, we have 2 Facts that tell us the same thing: the line intercepts the origin (0,0), but we don't know about the slope. We could have a NO or a YES answer.
Combined, INSUFFICIENT

Final Answer: E

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by Mathsbuddy » Sun Dec 08, 2013 6:24 pm
I have corrected my previous response here:

A single intercept has no bearing on the slope (gradient) of a line, so statements 1 and 2 would suggest insufficient. However, a line restricted to intersecting at x = 0 would have to be non-horizontal.

So:
Statement 1 - NO = sufficient
Statement 2 - MAYBE = insufficient
Statements combined - NO = sufficient
Last edited by Mathsbuddy on Sun Dec 08, 2013 11:52 pm, edited 1 time in total.
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by Uva@90 » Sun Dec 08, 2013 8:35 pm
[email protected] wrote:Hi shibsriz,

This DS question asks if a line has a slope of 0. This essentially asks "Is the line horizontal?" This is a YES/NO question.

Fact 1: The X-intercept is 0

This means that the line intercepts the X-axis at the origin (0,0). Unfortunately, we don't know anything else about the line. The slope could be positive (answer is NO), negative (answer is NO) or 0 (answer is YES).
Fact 1 is INSUFFICIENT

Fact 2: The Y-intercept is 0

This also means that the line intercepts the origin (0,0). We still don't know if the slope is positive, negative or 0.
Fact 2 is INSUFFICIENT

Combined, we have 2 Facts that tell us the same thing: the line intercepts the origin (0,0), but we don't know about the slope. We could have a NO or a YES answer.
Combined, INSUFFICIENT

Final Answer: E

GMAT assassins aren't born, they're made,
Rich
Hi Rich,
I have a doubt here,
What question ask us
"Is the line horizontal?"
that's what even you stated.

Statement 1: The X-intercept is 0
Doesn't it mean line is not horizontal.
Which is sufficient to say. NO

Hence Answer should be A only na ?

Could you please explain me where I went wrong ?

Thanks in advance.

Regards,
Uva.
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by [email protected] » Sun Dec 08, 2013 10:18 pm
Hi Uva,

With an X-intercept of 0, we know one place that the line "hits" (the origin - 0,0). Here are two examples of lines that fit this description:

Y = X is a line with a slope of 1 that passes through the origin.

Y = 0 is a horizontal line with a slope of 0 that passes through the origin.

Either of these lines fits the description given in Fact 1. The first gets us a "no" answer, the second gets us a "yes" answer.

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by Mathsbuddy » Sun Dec 08, 2013 11:54 pm
Uva@90 wrote:
[email protected] wrote:Hi shibsriz,

This DS question asks if a line has a slope of 0. This essentially asks "Is the line horizontal?" This is a YES/NO question.

Fact 1: The X-intercept is 0

This means that the line intercepts the X-axis at the origin (0,0). Unfortunately, we don't know anything else about the line. The slope could be positive (answer is NO), negative (answer is NO) or 0 (answer is YES).
Fact 1 is INSUFFICIENT

Fact 2: The Y-intercept is 0

This also means that the line intercepts the origin (0,0). We still don't know if the slope is positive, negative or 0.
Fact 2 is INSUFFICIENT

Combined, we have 2 Facts that tell us the same thing: the line intercepts the origin (0,0), but we don't know about the slope. We could have a NO or a YES answer.
Combined, INSUFFICIENT

Final Answer: E

GMAT assassins aren't born, they're made,
Rich
Hi Rich,
I have a doubt here,
What question ask us
"Is the line horizontal?"
that's what even you stated.

Statement 1: The X-intercept is 0
Doesn't it mean line is not horizontal.
Which is sufficient to say. NO

Hence Answer should be A only na ?

Could you please explain me where I went wrong ?

Thanks in advance.

Regards,
Uva.
A fine point you make Uva. I have corrected my previouys post.
I now believe:

Statement 1 - NO = sufficient
Statement 2 - MAYBE = insufficient
Statements combined - NO = sufficient
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