Multiple choice

Find the wrong term in the series given below: 1, 9, 33, 105, 158

  1. 158

  2. 105

  3. 33

  4. 9
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A Correct answer
Explanation

The pattern is: 1*2+7=9, 9*3+6=33, 33*4+5=137. The term 105 is incorrect; it should be 137. Following the pattern 137*5+4=689, the series is inconsistent.

AI explanation

The differences between the consecutive terms of the series are calculated as 9 minus 1 equals 8, 33 minus 9 equals 24 and 105 minus 33 equals 72. These differences of 8, 24 and 72 form a geometric progression where each difference is multiplied by 3 to get the next difference. Following this pattern, the next difference should be 72 multiplied by 3, which is 216. Adding this difference to the last correct term, 105 plus 216 equals 321. Since 158 is not 321, it is the wrong term in the series.

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