What should come in the place of question mark (?) in the following alpha numeric series?
10M-30, 15O-27, 20K-24, 25Q-21, ?
Show answer & explanation
Correct answer: D
Explanation
Number pattern
First numbers:
10 → 15 → 20 → 25 → 30 (+5 each)
Last numbers:
30 → 27 → 24 → 21 → 18 (−3 each)
So next term must have:
30 - 18
Letter pattern
Letters:
M → O → K → Q → ?
Positions:
M(13), O(15), K(11), Q(17)
Pattern:
+2, −4, +6 …
So next:
17 − 8 = 9 → I
Answer:
30I-18
Hence the correct answer is option 4.