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Bunuel
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Chethan92
Mapping the co-ordinates will give a right-angled triangle in the I quadrant.

Since we need to calculate the points inside the triangle, the base will be of length 31-1-1 = 29.
Next line will have 28 points, 27 and so on.

Total points = 29*30/2 = 435.

A is the answer.


Hi
Could you please explain the steps as your method seems to be really quick and easy to solve?
Could you please explain the step where you calculated the total points?
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riagarg07
Chethan92
Mapping the co-ordinates will give a right-angled triangle in the I quadrant.

Since we need to calculate the points inside the triangle, the base will be of length 31-1-1 = 29.
Next line will have 28 points, 27 and so on.

Total points = 29*30/2 = 435.

A is the answer.


Hi
Could you please explain the steps as your method seems to be really quick and easy to solve?
Could you please explain the step where you calculated the total points?

riagarg07

The method explained in short has been well explained in detail in the video. You may watch it for clear understanding.
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Hi Bunuel GMATinsight,

I chose to do the latter part of the question using Combinatorics.

To find the points that lie within the triangular region formed, we use x+y <31

Now, this gives us 15 possible values of x and 15 possible values of y (It is given that x & y are integers) i.e 30 values in total from which any 2 values can be picked (pls note: possible values include integers from 1-15 inclusive)

Using the formula, we get 30C2
Solving: 30!/28!x2!=435

Please let me know whether this way of solving is correct.

Thank you :)
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