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Railways PYQCBT 1 2016

RRB NTPC · Question 95

Find the value of 6 + 11 + 16 + 21 + … + 71. A. 539 B. 561 C. 661 D. 639

  1. A

  2. D

  3. B

  4. C

Show answer & explanation

Answer: (A) A

Explanation

This is an arithmetic series with first term 6, common difference 5 and last term 71, so it has (71 − 6)/5 + 1 = 14 terms. Sum = 14 × (6 + 71)/2 = 14 × 38.5 = 539.