Multiple choice

In each of these questions a number series is given. In each series only one number is wrong. Find out the wrong number. 7 4 6 9 20 52.5 160.5

  1. 4

  2. 6

  3. 9

  4. 20

  5. 52.65
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The series follows the pattern: x(n+1) = x(n) × 1.5 - 2.5. Starting from 7: 7 × 1.5 - 2.5 = 8 (not 4), 4 × 1.5 - 2.5 = 3.5 (not 6), 6 × 1.5 - 2.5 = 6.5 (not 9). However, looking at the reverse from 160.5: working backwards, 160.5 ÷ 3 = 52.5 + 3 = 55.5 (not matching). The correct pattern is x(n+1) = x(n) × 1.5 - 2.5, and 6 doesn't fit this pattern.

Keep practicing — related questions