Multiple choice

Find out the wrong number in the following number series. 4 2.5 3.5 6.5 15.5 41.25 126.75

  1. 2.5

  2. 3.5

  3. 6.5

  4. 15.5

  5. 41.25
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The series follows the pattern: each term (from 2nd onward) = previous term × 3^1 - 9.5, × 3^2 - 28.5, × 3^3 - 85.5, and so on, where the subtrahend triples each time (× 3). Applying this: 2.5 = 4 - 1.5; 3.5 = 2.5 × 3 - 4; 6.5 ≠ 3.5 × 3 - 8.5 (should be 2); 15.5 = 2 × 3 - 0.5. The number 6.5 breaks the pattern.

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