Which letter-cluster will replace the question mark (?) to complete the given series?
ZYXW, STUV, RQPO, ?, JIHG, CDEF
Letter Series Pattern Deconstruction
The series consists of 4-letter blocks: ZYXW, STUV, RQPO, ?, JIHG, CDEF. We need to identify the pattern governing these blocks.
Identify Block Patterns
The blocks follow alternating internal patterns:
- Descending: Letters decrease alphabetically (e.g., ZYXW).
- Ascending: Letters increase alphabetically (e.g., STUV).
The series alternates: Descending (ZYXW), Ascending (STUV), Descending (RQPO), ? (Ascending), Descending (JIHG), Ascending (CDEF).
Analyze First Letter Sequence Differences
Consider the first letter of each block and its alphabetical position (A=1, Z=26):
| Block | First Letter | Position |
| ZYXW | Z | 26 |
| STUV | S | 19 |
| RQPO | R | 18 |
| ? | ? | ? |
| JIHG | J | 10 |
| CDEF | C | 3 |
The differences between consecutive starting letter positions are:
- 26 -> 19: -7
- 19 -> 18: -1
- 18 -> ?: ?
- ? -> 10: ?
- 10 -> 3: -7
This reveals a repeating difference pattern: -7, -1.
Determine Missing Ascending Block
Based on the pattern -7, -1, the next difference after 18 should be -7:
- Starting position of ? = 18 + (-7) = 11
The 11th letter is K. The missing block must start with K.
As established, this position requires an ascending block. The ascending sequence starting with K is KLMN.
Verify KLMN Replacement in Series
The complete series: ZYXW, STUV, RQPO, KLMN, JIHG, CDEF.
- Internal patterns: Descending, Ascending, Descending, Ascending, Descending, Ascending. (Matches)
- First letter sequence: Z(26), S(19), R(18), K(11), J(10), C(3).
- Differences: -7, -1, -7, -1, -7. (Matches)
The cluster KLMN correctly completes the series.
Important Questions from Alphabet Series
Select the combination of letters that when sequentially placed in the blanks of the given series will complete the series.
G _ C T _ X _ T G X _ T _ X C T G _ C T
Select the combination of letters that when sequentially placed in the blanks of the given series will complete the series.
Q _ P _ M _ A _ T _ Q A _ T M
Select the combination of letters that when sequentially placed in the blanks of the given series will complete the series.
r _ x l _ q _ _ x _ p q _ e _ l p _
Select the letter-cluster from among the given options that can replace the question mark (?) in the following series.
BKR, DNV, FQZ, ?, JWH
Select the letter-cluster from among the given options that can replace the question mark (?) in the following series.
AU, BO, CI, DE, ?
