Rodrigo wrote:On the X,Y plane, how many of the points on line segment PQ have coordinates that are both integers?
y axis: P=(0,30)
x axis: Q=(50,0)
(A) 5
(B) 8
(C) 10
(D) 11
(E) 20
Thank you in advance!
X,Y Plane
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Put the equation in the form y =mx +b, where m is slope =-3/5 and b is y intercept = 30Rodrigo wrote:On the X,Y plane, how many of the points on line segment PQ have coordinates that are both integers?
y axis: P=(0,30)
x axis: Q=(50,0)
(A) 5
(B) 8
(C) 10
(D) 11
(E) 20
Thank you in advance!
y= -3X/5+30
Y is an interger only if X is a multiple of 5. This is another way of asking how many multiples of 5 are there between 0 and 50 inclusive. 10 is a trap if you think zero is not a multiple of 5, or if you don't count your smallest finger as 0.
D. 11.
On a question like this if the ideas are not forthcoming, just do the simplest thing you can with the question first. That if given two points, you can find the slope. Now once you have slope, it may trigger an idea such as mx + b or something else about slope and lines. But never just stare at the problem thinking a way out. There has got to be a simple obvious first step to any GMAT problem. Do that and build from there.
Hope this helps.
