Medium MCQ +4 / -1 PYQ · JEE Mains 2020

If the sum of the first 40 terms of the series,
3 + 4 + 8 + 9 + 13 + 14 + 18 + 19 + ..... is (102)m, then m is equal to :

  1. A 20 Correct answer
  2. B 5
  3. C 10
  4. D 25

Solution

3 + 4 + 8 + 9 + 13 + 14 +…….upto 40 terms <br><br>$\Rightarrow$ 7 + 17 + 27 +…….20 terms <br><br>S = ${{20} \over 2}$ [2 × 7 + 19 × 10] <br><br> = 102 × 20 = 102 m <br><br>$\therefore$ m = 20

About this question

Subject: Mathematics · Chapter: Sequences and Series · Topic: Arithmetic Progression

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