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Is the slope of line z positive?

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by M7MBA » Tue Jun 25, 2019 5:57 am

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Is the slope of line z positive?

1) line m is perpendicular to line z, and its slope is \(−\dfrac{1}{4}\)

2) line z's y-intercept is positive

The OA is the option _A_

Source: Veritas Prep
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Source: — Data Sufficiency |

by Ian Stewart » Thu Jun 27, 2019 7:27 am
It's hard to guess which line has the slope of -1/4 in Statement 1. If they're talking about line z, then the Statement is clearly sufficient. If they're talking about line m, then since perpendicular lines have slopes that are negative reciprocals of each other, line z would have a slope of 4. So regardless of what that sentence means, it's sufficient alone. Statement 2 is useless on its own, since knowing about just one point on a line tells you nothing about the line's slope, so the answer is A.
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