Triangles are my favorite shape: GMAT Question of the Day

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Triangles are my favorite shape: GMAT Question of the Day

GMAT question of the day: Problem Solving
Explanation
To join the two tracks, we need to take two points on one track and one point on the other to form a triangle; we cannot use three points from one track. Since the order of the points doesn't matter, we use the formula for combinations.

We can take 2 points from the first track and 1 point from the second = 6C2 * 10C1 = 150 ways. We can take 1 point from the first track and 2 points from the second = 6C1 * 10C2 = 270 ways.

Thus, the total number of ways of forming a triangle is 150 + 270 = 420.

The correct choice is E.

Three points where two lines meet…