Multiple choice

Find the wrong term in sequence : 1, 3, 7, 15, 27, 63, 127

  1. 7

  2. 15

  3. 27

  4. 63

  5. 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pattern is 2^n - 1: 2^1-1=1, 2^2-1=3, 2^3-1=7, 2^4-1=15, 2^5-1=31 (not 27), 2^6-1=63, 2^7-1=127. Thus, 27 is the wrong term.

AI explanation

The series follows the logic of multiplying the previous term by 2 and adding 1. Applying this gives 1, 3, 7, 15, 31, 63, and 127. Since the correct calculation for the fifth term is (15 * 2) + 1 = 31, the number 27 is the wrong term.

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