Letter Series Pattern Analysis

The question presents a series of letter clusters: ABZY, CDXW, EFVU, ?, IJRQ. We need to identify the pattern governing this series to find the missing cluster.

Identifying the Pattern

Let's break down each cluster and observe the pattern:

• First Cluster (ABZY):
  • The first two letters, 'A' and 'B', are consecutive letters from the beginning of the alphabet (positions $1^{st}$ and $2^{nd}$).
  • The last two letters, 'Z' and 'Y', are consecutive letters from the end of the alphabet, in reverse order (positions $26^{th}$ and $25^{th}$).
• Second Cluster (CDXW):
  • The first two letters, 'C' and 'D', are the next consecutive pair in the alphabet (positions $3^{rd}$ and $4^{th}$).
  • The last two letters, 'X' and 'W', are the next consecutive pair from the end of the alphabet, in reverse order (positions $24^{th}$ and $23^{rd}$).
• Third Cluster (EFVU):
  • The first two letters, 'E' and 'F', continue the sequence (positions $5^{th}$ and $6^{th}$).
  • The last two letters, 'V' and 'U', continue the reverse sequence from the end (positions $22^{nd}$ and $21^{th}$).

Applying the Pattern to Find the Missing Cluster

Based on the observed pattern:

1. First Two Letters: The sequence progresses as AB, CD, EF. The next pair should be GH (positions $7^{th}$ and $8^{th}$).
2. Last Two Letters: The sequence progresses backwards from the end as ZY, XW, VU. The next pair should be TS (positions $20^{th}$ and $19^{th}$).
3. Combining the Pairs: Putting these together, the missing cluster should be GH followed by TS, which is GHTS.

Verifying with the Final Cluster

Let's check if the next cluster in the series, IJRQ, fits the pattern following GHTS:

• Following GH: The next pair should be IJ (positions $9^{th}$ and $10^{th}$). This matches the first two letters of IJRQ.
• Following TS: The next pair from the end should be RQ (positions $18^{th}$ and $17^{th}$). This matches the last two letters of IJRQ.

The pattern holds true. Therefore, the missing letter cluster is GHTS.