bubbliiiiiiii wrote:Lines n and p lie on the xy plane. Is the slope of line n less than slope of line p
(1) Lines n and p intersect at (5, 1)
(2) The y-intercept of line n is greater than the y intercept of p

Though this one is discussed earlier .. can someone give a better approach and confirm the answer?

Some say C and some say E.

This one appears to be a GMAT prep 700+ problem.

Experts guidance please.

Hi bubbliiiiiiii!

I'm assuming that you understood that each statement alone was insufficient (because you eliminated A, B and D from your question) - BUT I will discuss the overall approach for each statement here as well.

With regard to approach,

Step One: if you read coordinate geometry, immediately consider sketching
Step Two: this is a Yes/No question so our test for insufficiency will need to try to find BOTH a Yes and a No scenario.

Statement (1): Sketch a coordinate plane and put at point at (5,1). Now draw ANY two lines through the point (5,1) and label them N and P. Is the slope of N greater than that of P? Now swap the labels for your line (name the n line with a p now and the p line with an n). The answer just changed - Insufficient!

Statement (2): Same idea, sketch a coordinate plane and put 2 dots on the Y-axis (anywhere you want). Label the higher one N and the lower one P. Now draw 2 lines any way you want. Is the slope of your N line greater than your P line? If you answer Yes, then rotate the P line until the answer is No (and vice versa). We were able to answer BOTH Yes and No - Insufficient.

Statements (Together): Again, the idea is to use our sketch to find AN answer (either yes or no, doesn't matter). And then try to re-sketch the drawing to get the OTHER answer. So, sketch a quick coordinate plane, plot the point (5,1) and then put 2 dots on the Y-axis (anywhere you want) and label the higher one N. Draw your lines - is the slope of N less than P? Now using your 2 fingers for lines, try to keep moving the pair of lines up and down the Y-axis or further apart/closer together on the axis. Can you find a way to get N to have a GREATER slope than P? You're start to see that whatever happens, N will always be at least slightly less than P (or more negative if you have negative slopes).

So, strategy: Geometry (particularly coordinate geo) make a sketch. Yes/No DS problems, work to prove insufficiency - if you cannot, then bets are that it is sufficient.


Whit