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There are 10 points in a plane, out of these 6 are collinear. If N is the number of triangles formed by joining these points. Then:

1. N ≤ 100
2. 100 < N ≤ 140
3. 140 < N ≤ 190
4. N > 190

Correct answer: N ≤ 100

Solution

To form a triangle, we need to select 3 points. However, if all 3 points are chosen from the 6 collinear points, they will not form a triangle. The total combinations of 3 points from 10 is 120, but we must subtract the combinations of 3 points from the 6 collinear points, which is 20. Thus, the maximum number of triangles that can be formed is 100.

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