Multiple choice

In the following number series, a wrong number is given. Find out that wrong number. 34 50 74 115 178 274

  1. 34

  2. 50

  3. 74

  4. 115

  5. No wrong number
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let's check the pattern: 50 - 34 = 16, 74 - 50 = 24, 115 - 74 = 41, 178 - 115 = 63, 274 - 178 = 96. The differences are 16, 24, 41, 63, 96. Second differences: 8, 17, 22, 33 - not consistent. Try multiplying: 34 × 1.5 = 51 (close to 50), 50 × 1.5 = 75 (close to 74), 74 × 1.5 = 111 (not 115), 115 × 1.5 = 172.5 (not 178). If pattern was ×1.5 then +1: 34×1.5+1=52, not 50. Try: 34 + 16 = 50, 50 + 24 = 74, 74 + 41 = 115. Notice 16 = 4^2, 24 ≠ 5^2 (should be 25). If 50 + 25 = 75, then 75 + 36 = 111, 111 + 49 = 160... But we have 115. The number 115 breaks this pattern.

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