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Let a 1 , a 2 , a 3 , … a n , … ,be in A.P. If a 3 + a 7 + a 11 + a 15 = 72 , then the sum of its first 17 terms is equal to :

Options

  1. A306
  2. B204
  3. C153
  4. D612

Correct answer

A. 306

Step-by-step solution

a 3 + a 7 + a 11 + a 15 = 72 a 3 + a 15 + a 7 + a 11 = 72 a 3 + a 15 = a 7 + a 11 = a 1 + a 17 a 1 + a 17 = 36 S 17 = 17 2 a 1 + a 17 = 17 × 18 = 306

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