1. Choice (d) is correct.  Given, ⁿ ⁺ ¹C₃ = 3.ⁿ C₂ (n + 1)!/(n + 1 - 3)! × 3! = (3)× (n)!/ (n - 2)! × 2! ⇒ (n + 1) × (n)!/(n - 2)! ×3 ×2! = 3 × (n)!/(n-2)! × 2! ⇒ n + 1/3 = 3 ⇒ n + 1 = 9 ⇒ n = 8 Class 11th NCERT. From the Chapter 6: Permutations and Combinations. Give answer according to your understanRead more

    Choice (d) is correct. 
    Given, ⁿ ⁺ ¹C₃ = 3.ⁿ C₂
    (n + 1)!/(n + 1 – 3)! × 3! = (3)× (n)!/ (n – 2)! × 2! ⇒ (n + 1) × (n)!/(n – 2)! ×3 ×2! = 3 × (n)!/(n-2)! × 2!
    ⇒ n + 1/3 = 3 ⇒ n + 1 = 9 ⇒ n = 8
    Class 11th NCERT. From the Chapter 6: Permutations and Combinations. Give answer according to your understanding.

    For more please visit here:
    https://www.tiwariacademy.com/ncert-solutions/class-11/maths/#chapter-6

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    • 6
  2. Choice (c) is correct.  It is same as selecting 6 boys out of 11 boys or selecting 5 boys out of 11 boys.  Number of ways of forming groups = ¹¹C₆ or ¹¹C₅  This question related to Chapter 6 maths Class 11th NCERT. From the Chapter 6: Permutations and Combinations. Give answer according to your undeRead more

    Choice (c) is correct. 
    It is same as selecting 6 boys out of 11 boys or selecting 5 boys out of 11 boys. 
    Number of ways of forming groups = ¹¹C₆ or ¹¹C₅ 
    This question related to Chapter 6 maths Class 11th NCERT. From the Chapter 6: Permutations and Combinations. Give answer according to your understanding.

    For more please visit here:
    https://www.tiwariacademy.com/ncert-solutions/class-11/maths/#chapter-6

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    • 14
  3. Choice (b) is correct A parallelogram is formed by choosing 2 straight lines from the set of m parallel lines and 2 straight lines from the set of n parallel lines.  Number of parallelograms = ᵐC₂  × ⁿC₂  = m(m - 1)/2 × n(n - 1)/2 This question related to Chapter 6 maths Class 11th NCERT. From the CRead more

    Choice (b) is correct
    A parallelogram is formed by choosing 2 straight lines from the set of m parallel lines and 2 straight lines from the set of n parallel lines. 
    Number of parallelograms = ᵐC₂  × ⁿC₂  = m(m – 1)/2 × n(n – 1)/2
    This question related to Chapter 6 maths Class 11th NCERT. From the Chapter 6: Permutations and Combinations. Give answer according to your understanding.

    For more please visit here:
    https://www.tiwariacademy.com/ncert-solutions/class-11/maths/#chapter-6

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    • 6
  4. Choice (b) is correct. Since the points lie on a circle, so on three points are collinear. Chord can be drawn by the combination of two points.  Number of chords = ¹⁵ C ₂ = 15 × 14 / 1 × 2 = 105 This question related to Chapter 6 maths Class 11th NCERT. From the Chapter 6: Permutations and CombinatiRead more

    Choice (b) is correct.
    Since the points lie on a circle, so on three points are collinear. Chord can be drawn by the combination of two points. 
    Number of chords = ¹⁵ C ₂ = 15 × 14 / 1 × 2 = 105
    This question related to Chapter 6 maths Class 11th NCERT. From the Chapter 6: Permutations and Combinations. Give answer according to your understanding.

    For more please visit here:
    https://www.tiwariacademy.com/ncert-solutions/class-11/maths/#chapter-6

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    • 15
  5. Choice (a) is correct Given, ⁿP₃ : ⁿP₄ = 1 : 5  ⇒ ⁿP₃/ ⁿP₄ = 1/5 ⇒ (n!/(n -3)!)/ (n!/ (n - 4)!) = 1/5 ⇒ (n - 4)!/ (n -3)! = 1/5 ⇒ (n - 4)! / (n - 3) (n - 4)! = 1/5 ⇒ 1 / n - 3 = 1/5 ⇒ n - 3 = 5 ⇒ n = 8  This question related to Chapter 6 maths Class 11th NCERT. From the Chapter 6: Permutations and CRead more

    Choice (a) is correct
    Given, ⁿP₃ : ⁿP₄ = 1 : 5 
    ⇒ ⁿP₃/ ⁿP₄ = 1/5 ⇒ (n!/(n -3)!)/ (n!/ (n – 4)!) = 1/5 ⇒ (n – 4)!/ (n -3)! = 1/5
    ⇒ (n – 4)! / (n – 3) (n – 4)! = 1/5 ⇒ 1 / n – 3 = 1/5
    ⇒ n – 3 = 5 ⇒ n = 8 
    This question related to Chapter 6 maths Class 11th NCERT. From the Chapter 6: Permutations and Combinations. Give answer according to your understanding.

    For more please visit here:
    https://www.tiwariacademy.com/ncert-solutions/class-11/maths/#chapter-6

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    • 7