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KVPY2010MathematicsProbability

Three vertices are chosen randomly from the seven vertices of a regular 7-sided polygon. The probability that they form the vertices of an isosceles triangle is-

Options

  1. A1 7
  2. B1 3
  3. C3 7
  4. D3 5

Correct answer

D. 3 5

Step-by-step solution

AGB , AFC & AED are isosceles P= ⁷ C ₁ 3 ⁷ C ₃ = 7 3 7 6 5 3 2 = 3 5

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