Slope of a Line

This topic has expert replies
User avatar
Senior | Next Rank: 100 Posts
Posts: 72
Joined: Tue Apr 19, 2011 6:58 am
Followed by:6 members

Slope of a Line

by jayanti » Mon Aug 08, 2011 10:26 pm
Lines k and m are parallel to each other. Is the slope of line k positive?

(1) Line k passes through the point (3, 2).
(2) Line m passes through the point (-3, 2).
Source: — Data Sufficiency |

Senior | Next Rank: 100 Posts
Posts: 47
Joined: Wed Sep 03, 2008 11:18 pm
Thanked: 5 times
Followed by:1 members

by top_business_2011 » Tue Aug 09, 2011 12:37 am
jayanti wrote:Lines k and m are parallel to each other. Is the slope of line k positive?

(1) Line k passes through the point (3, 2).
(2) Line m passes through the point (-3, 2).
Given: Line K and Line M are parallel to each other = Slopes of line K and line M are equal
Required: Is slope of line K positive?

Though this question can be solved algebraically, I suggest solving it through rough sketching of an X-Y plane and placing the coordinates.

Statement 1: It only gives one point on line K; Hence, insufficient.
Statement 2: Not different from the above; Hence, insufficient.

Both: Once again insufficient, as the lines can have both positive, both negative, or both 0 slopes.

Hence, the answer is E.

Solving it algebraically tells you that the sum of the y-intercepts is 4.[You can determine the value even by the graphic approach suggested above].

User avatar
Legendary Member
Posts: 540
Joined: Sat Dec 20, 2008 7:24 pm
Thanked: 37 times
Followed by:6 members

by navami » Tue Aug 09, 2011 4:21 am
Ans should be E.

now there are two lines.
and we know that they are parallel.
line 1 passes through one point - which might have slope as + ve or -ve.
line 2 which is parallel to line 1 passes through a different point might aswell have +ve or -Ve slope.
This time no looking back!!!
Navami