Question

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 :

• A. N = 100
• B. 100 < N $\le$ 140
• C. 140 < N $\le$ 190
• D. N > 190

Answer 1

Answer: (A)

N = 100

Answer 2

$^{10}C_{3} - ^{6}C_{3}$ $= \frac{10\times9\times8}{6}- \frac{6\times5\times4}{6} = 120 - 20 = 100$