Let's analyze the pattern in the given series: C9K, E19I, G39G, I79E, L159C. Each term consists of a letter, followed by a number, and then another letter. We will examine the pattern for each component separately.

Analyzing the Series Pattern

• First Letter: C, E, G, I, L

  Let's look at the alphabetical position of these letters:

  • C is the 3rd letter.
  • E is the 5th letter.
  • G is the 7th letter.
  • I is the 9th letter.
  • L is the 12th letter.

  The differences in position are: \(5 - 3 = 2\), \(7 - 5 = 2\), \(9 - 7 = 2\), \(12 - 9 = 3\). The pattern for the first letter seems to be adding 2 to the alphabetical position, except for the last term where it adds 3.

• Number: 9, 19, 39, 79, 159

  Let's see how these numbers are related:

  • \(9 \times 2 + 1 = 18 + 1 = 19\)
  • \(19 \times 2 + 1 = 38 + 1 = 39\)
  • \(39 \times 2 + 1 = 78 + 1 = 79\)
  • \(79 \times 2 + 1 = 158 + 1 = 159\)

  The pattern for the number is consistent: multiply the previous number by 2 and add 1.

• Second Letter: K, I, G, E, C

  Let's look at the alphabetical position of these letters:

  • K is the 11th letter.
  • I is the 9th letter.
  • G is the 7th letter.
  • E is the 5th letter.
  • C is the 3rd letter.

  The differences in position are: \(9 - 11 = -2\), \(7 - 9 = -2\), \(5 - 7 = -2\), \(3 - 5 = -2\). The pattern for the second letter is consistent: subtract 2 from the alphabetical position of the previous letter.

Identifying the Wrong Term in the Series

Based on the analysis, the number pattern and the second letter pattern are consistent throughout the series. The first letter pattern is adding 2 to the alphabetical position for the first four terms (C, E, G, I). If this pattern were to continue, the first letter of the fifth term should be the letter that is 2 positions after 'I' (which is the 9th letter), i.e., the \(9 + 2 = 11\)th letter, which is 'K'.

The last term given in the series is L159C. While the number (159) and the second letter (C) follow the established patterns, the first letter is 'L' (12th letter), which is 3 positions after 'I' (\(9 + 3 = 12\)), not 2.

Therefore, the term that breaks the pattern is L159C because its first letter does not follow the consistent +2 pattern of the first letters in the preceding terms.

The inconsistency is clearly in the first letter of the term L159C.

Revision Table: Series Pattern Analysis

Understanding alphanumeric series patterns is crucial for logical reasoning questions. Key steps involve:

• Break down each term into its components (letters, numbers).
• Analyze the sequence of each component separately.
• Look for arithmetic, geometric, or other specific patterns (like multiplying/dividing by a number, adding/subtracting a number, sequential changes, positional values of letters).
• Identify which term does not follow the established pattern of the majority of the series.

Additional Information on Pattern Recognition

Series questions test your ability to find underlying rules. Common patterns include:

• Letter Series: Based on alphabetical position, skipping letters, reverse order, alternating patterns.
• Number Series: Arithmetic progressions (constant difference), geometric progressions (constant ratio), square numbers, cube numbers, prime numbers, Fibonacci sequence, or a combination of operations (like in this question, multiply and add).
• Alphanumeric Series: Combining letter and number patterns, often independently or sometimes related.

Practicing various types of series helps in quickly identifying the pattern and the odd term out or the next term in the series.