Multiple choice

Find the wrong term in the following number series. $80, 105, 195, 478, 1350, 3975$

  1. 1350

  2. 3975

  3. 195

  4. 478

  5. 80
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The series follows the pattern: multiply by 1.5 and add increasing odd numbers starting from 15. 80×1.5+15=135 (should be 105, error), 105×1.5+30=187.5 (not 195). The actual pattern is: ×1.5+15, ×2-15, ×2.5-45, ×3-74... The term 478 breaks this pattern and should be 497.5.

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