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In the rectangular coordinate system shown above, does the line \(k\) (not shown) intersect quadrant \(\rm II?\)

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by Vincen » Thu Sep 23, 2021 11:31 am

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GMAT_DS_PREP_100.png
In the rectangular coordinate system shown above, does the line \(k\) (not shown) intersect quadrant \(\rm II?\)

(1) The slope of \(k\) is \(-\dfrac16.\)

(2) The \(y\)-intercept of \(k\) is \(-6.\)

Answer: A

Source: GMAT Prep
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Source: — Data Sufficiency |

Vincen wrote:
Thu Sep 23, 2021 11:31 am
GMAT_DS_PREP_100.png

In the rectangular coordinate system shown above, does the line \(k\) (not shown) intersect quadrant \(\rm II?\)

(1) The slope of \(k\) is \(-\dfrac16.\)

(2) The \(y\)-intercept of \(k\) is \(-6.\)

Answer: A

Source: GMAT Prep
Target question: Does line k intersect quadrant II?

Statement 1: The slope of k is -1/6
Here are a few lines with slope -1/6
Image
KEY CONCEPT: As we travel from right to left along a line with slope -1/6, we keep moving up.
So, at some point, the line will surely pass through quadrant II
So, the answer to the target question is YES, line k DOES intersect quadrant II
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: The y-intercept of k is -6
There are several possible cases that satisfy statement 2. Here are two:
Case a: The line is horizontal (i.e., has slope zero)
Image
In this case, the answer to the target question is NO, line k does NOT intersect quadrant II

Case b: The line looks like this
Image
In this case, the answer to the target question is YES, line k DOES intersect quadrant II

Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer: A

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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