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Railways PYQCBT 1 2016

RRB NTPC · Question 72

Find the missing (?) in the series. 3, 5, 9, ?, 33, 65………. A. 23 B. 21 C. 17 D. 15

  1. D

  2. B

  3. A

  4. C

Show answer & explanation

Answer: (D) C

Explanation

Each term is a power of 2 plus 1: 2 + 1 = 3, 4 + 1 = 5, 8 + 1 = 9, 16 + 1 = 17, 32 + 1 = 33, 64 + 1 = 65 (equivalently, each term is twice the previous minus 1). The missing term is 17.