Which letter cluster will replace the question mark (?) in the following series?
RUO, OQJ, ?, IIZ, FEU, CAP
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → LME
Each position of the cluster is checked on its own; when the count goes back past A it continues from Z.
First letters R (18), O (15), ?, I (9), F (6), C (3): 3 places back each time, so the missing letter is \(15-3=12\), L
Second letters U (21), Q (17), ?, I (9), E (5), A (1): 4 places back each time, so the missing letter is \(17-4=13\), M
Third letters O (15), J (10): 5 places back, so the rule is 5 places back and the missing letter is \(10-5=5\), E
The rest of the third letters agree: 5 back from E are D, C, B, A, Z; 5 back from Z (26) is U (21); 5 back from U is P (16)
So the missing cluster is LME.