in the xy-plane, is the slope of line k equal to 0?

[diana324sf]

In the xy-plane, is the slope of line k equal to 0?

(1) the x-intercept of k is 0
(2) the y-intercept of k is 0

The OA is E.

I thought the first statement (the x-intercept is 0) implies that there is only one intercept. However, from the answer, it seems that the x-intercept of 0 can be one of infinitely many intercepts. Should we assume on the exam when it says something is the x-intercept, there can be more than one?

Thanks!

[nileshdalvimumbai]

No, x- intercept is when you equal y to zero and if the x intercept is zero then the point is the origin. Now, you can have infinitely many lines passing through origin with different slopes. So, it is not sufficient to establish that the line is parallel to x- axis.

Same with y and same with both combined. All lead to the fact that the point under discussion is the origin and many lines can pass through it. I say infinitely many because x and y are not necessarily integers. Either way, E is the answer.

[chawinping]

I'd like to help post the screenshot.



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[RonPurewal]

I'd like to help post the screenshot.



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thanks, chawinping.

do you happen to have the answer explanation from the software?
that's what i would love to see.

this problem is disgusting -- if they wrote "THE x-intercept" (a wording that clearly implies a single point) but are allowing multiple x-intercepts, then that's just horrible. whoever wrote this one (not to mention whoever edited it) should be fired.

[chawinping]

Hi Ron,

Here's the corresponding answer explanation



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[RonPurewal]

Hi Ron,

Here's the corresponding answer explanation



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wow, unbelievable. perhaps i will write to gmac and see what they say.

[ffearth]

Let's suppose that there were no wording mistakes in the problem, shouldn't the answer be A?

statement 1: "The x-intercept of k is 0." The only possibility for the x intercept to be 0 is that line k has an equation of the form y=mx where m is different from 0. SUFFICIENT

statement 2: "The y-intercept of k is 0." The y-intercept of k could be 0 if the equation of the line were y=0 (and thus m=0) or if it were y=mx where m is different from 0. INSUFFICIENT

Is this correct?

Thank you

[RonPurewal]

Let's suppose that there were no wording mistakes in the problem, shouldn't the answer be A?

statement 1: "The x-intercept of k is 0." The only possibility for the x intercept to be 0 is that line k has an equation of the form y=mx where m is different from 0. SUFFICIENT

statement 2: "The y-intercept of k is 0." The y-intercept of k could be 0 if the equation of the line were y=0 (and thus m=0) or if it were y=mx where m is different from 0. INSUFFICIENT

Is this correct?

Thank you

that seems like the right understanding to me.

[devansh.anand]

Let's suppose that there were no wording mistakes in the problem, shouldn't the answer be A?

statement 1: "The x-intercept of k is 0." The only possibility for the x intercept to be 0 is that line k has an equation of the form y=mx where m is different from 0. SUFFICIENT

statement 2: "The y-intercept of k is 0." The y-intercept of k could be 0 if the equation of the line were y=0 (and thus m=0) or if it were y=mx where m is different from 0. INSUFFICIENT

Is this correct?

Thank you

that seems like the right understanding to me.

Wow I get to correct Ron. Alas, its not verbal. tch tch!

Statement 1 is not sufficient in itself. y=mx and y=b both satisfy the 1st statement.

Just prey you don't get this kind of a pathetic question, which is ambiguous at best, on the test day.
and
just make a mental not that GMAC treats X axis' intercept on X axis as 0 (or everything, 0 included -- this then contradicts 'THE' in the statement )

Best

[RonPurewal]

Wow I get to correct Ron. Alas, its not verbal. tch tch!

i didn't know this was a contest.

Statement 1 is not sufficient in itself. y=mx and y=b both satisfy the 1st statement.

no.
if you have a line whose equation is y = b (where b is nonzero), then that line is parallel to the x-axis, and so doesn't have an x-intercept (and thus can't satisfy the first statement).

[devansh.anand]

i didn't know this was a contest.

Far from it Ron. Have been a huge fan in fact. :)


On y=b. Agree, no x intercept (which does not mean 0 intercept)

[tim]

i don't think you've corrected Ron on anything here! i've kind of adopted a mindset where if it looks at first like Ron is wrong on the forums i probably just made a mistake. then i go back and look for my mistake, and i always find it! i recommend this approach to everyone; being able to accept that you must have done something wrong even if you don't see it yet is one of the most helpful things you can do in preparing for the GMAT (or just about anything in life).. :)

[devansh.anand]

i don't think you've corrected Ron on anything here! i've kind of adopted a mindset where if it looks at first like Ron is wrong on the forums i probably just made a mistake. then i go back and look for my mistake, and i always find it! i recommend this approach to everyone; being able to accept that you must have done something wrong even if you don't see it yet is one of the most helpful things you can do in preparing for the GMAT (or just about anything in life).. :)

True. Especially if its with Ron.

[jlucero]

Good stuff here.

[liarish]

Hey Ron,

Just wondering if you ever wrote to GMAC about this problem.

Also, I actually got this question right when I tried it. But something about the question was just off and I didn't quite understand the solution so I wanted to double check if my methodology was right, and then I came across this post.

This is how I approached this problem:

1. The x intercept = 0
so as y=mx+c , x intercept = 0 means y=0
-> 0=mx+c => mx= -c or -mx= c => so m could be +ve/-ve so the statement is Insufficient.

2. The y intercept = 0
y=mx+c, y intercept = 0 means x=0
-> y=c, coz mx=0 so m could be +ve/-ve so this statement is Insufficient.

Together :
x & y intercepts=0
y=mx+c, x=0 and y=0 => 0=0+c =>c=0 again m could be +ve/-ve anything. So Insufficient.
So came down to E as the answer.

Is my approach for this question (or similar questions) correct?
And how should this question be worded to actually make it a sound question?

Thanks