In the following series, only one letter-cluster is incorrect. Select the…
2025
In the following series, only one letter-cluster is incorrect. Select the INCORRECT letter-cluster.
QTM ORK MPI KNG ILF GJC
- A.
ORK
- B.
KNG
- C.
ILF
- D.
MPI
Attempted by 3 students.
Show answer & explanation
Correct answer: C
Concept: In a letter-cluster series, each three-letter group is built by applying a fixed pair of alphabet-position shifts — a constant forward step from the first letter to the second letter, and a constant backward step from the second letter to the third letter — identically across every genuine cluster (using A = 1, B = 2, ..., Z = 26).
Application: Convert every cluster in the series into its alphabet positions and compute both shifts:
Cluster | 1st letter | 2nd letter | 3rd letter | Shift 1→2 | Shift 2→3 |
|---|---|---|---|---|---|
QTM | Q (17) | T (20) | M (13) | +3 | −7 |
ORK | O (15) | R (18) | K (11) | +3 | −7 |
MPI | M (13) | P (16) | I (9) | +3 | −7 |
KNG | K (11) | N (14) | G (7) | +3 | −7 |
ILF | I (9) | L (12) | F (6) | +3 | −6 |
GJC | G (7) | J (10) | C (3) | +3 | −7 |
Five of the six clusters share the identical shift pair (+3, -7); one cluster shows (+3, -6) instead.
Cross-check: Apply the rule forward independently, starting from the first letter of the deviating cluster: I (9) + 3 = 12 = L, which matches the cluster’s own second letter; then L (12) - 7 = 5 = E, one position lower than the cluster’s actual third letter, F (6) - confirming the mismatch by direct construction rather than only by comparing the shift numbers.
Conclusion: The letter-cluster ILF does not follow the (+3, -7) shift pattern that every other cluster in the series follows, so ILF is the incorrect letter-cluster.