slope of line M

[gmatdriller]

If lines L and M are parallel on the x-y plane, what is the slope of line M?

(i) Line L passes through point (1, 1)
(ii) Line M passes through point (3, 2)

Do we need to calculate a specific value here?

OA is E

[eagleeye]

If lines L and M are parallel on the x-y plane, what is the slope of line M?

(i) Line L passes through point (1, 1)
(ii) Line M passes through point (3, 2)

Do we need to calculate a specific value here?

OA is C

OA is wrong here. My first instinct was to visualize and see two parallel equidistant lines passing through two points and I saw infinite lines. So I figured the answer is E. But after reading the answer supplied, I did it algebraically. I still got the answer as E. Please correct the OA.

Here's the explanation.

Since the two lines are parallel, they have the same slope. Let's call it m. So the general equation of the line is y=mx+c. With that in mind, let`s look at the statements:

(i) Line L passes through point (1, 1)
Let L be the y intercept of line L. Here y=mx+L
Since it passes through 1,1 =. 1=m+L.
Two unknowns in a single equation, Insufficient.


(ii) Line M passes through point (3, 2)
In the same way as above, let the equation be y=mx+M, then 2=3m+M.
Again, Two unknowns in a single equation, Insufficient.

Together we have:
1=m+L
2=3+M.

Two equations and three unknowns, still doesn`t have a unique solution. Insufficient.

So, the correct answer is E.

Let me know if this helps

[mdavidm_531]

OA is E.

Try drawing.

Two points: one at 1,1 and another one at 3,2

You can draw infinite possibilities of line l and m that are parallel - any angle.

This alone makes the data insufficient.

[gmatdriller]

OA is hereby corrected.