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11th Class Mathematics Sample Paper Mathematics Olympiad - Sample Paper-5

  • question_answer
    If 7 points out of 12 are in the same straight line, then the number of triangles formed is

    A) (a) 180                         

    B) (b) 185          

    C) (c) 181                         

    D) (d) 190

    Correct Answer: B

    Solution :

    [b] Required no. of triangles \[{{=}^{12}}{{C}_{3}}={{\,}^{7}}{{C}_{3}}=\frac{12\times 11\times 10}{3\times 2}-\frac{7\times 6\times 5}{3\times 2}=220-35=185\] Option [b] is correct.


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