Find the next term in the mixed alpha numeric series: YC3, XF6, WI9, ______.

Introduction / Context:
This is a mixed alpha numeric series question where each term consists of two letters followed by a number. To find the next term in the series, we need to examine how the letters and numbers change in each step. Such questions combine letter series skills with number series analysis, making them slightly more demanding.

Given Data / Assumptions:

• The given terms are YC3, XF6, and WI9.
• Each term follows the pattern letter letter number.
• The next term must continue the pattern for both letters and numbers simultaneously.
• Alphabetical positions run from A = 1 to Z = 26.

Concept / Approach:
We treat the first letters as one sequence, the second letters as another sequence, and the numbers as a third sequence. We look for a regular step, such as adding or subtracting a fixed value, in each of these three subsequences. If all three show a consistent pattern, we can project the next term.

Step-by-Step Solution:
Step 1: Examine the first letters: Y, X, W. Step 2: Their positions are Y = 25, X = 24, W = 23. This clearly shows a decrease of 1 each time. Step 3: Therefore, the next first letter must be 23 minus 1 equals 22, which corresponds to V. Step 4: Now examine the second letters: C, F, I. Step 5: Their positions are C = 3, F = 6, I = 9. The step size is plus 3 each time, since 3 to 6 and 6 to 9 are both plus 3. Step 6: Applying plus 3 again, 9 plus 3 equals 12, which corresponds to L. Thus, the second letter of the next term is L. Step 7: Finally, examine the numbers: 3, 6, 9. These form a simple arithmetic progression with a common difference of 3. Step 8: Adding 3 to 9 gives 12. So the numeric part of the next term is 12. Step 9: Combining all three results, the next term is VL12.

Verification / Alternative check:
As a quick verification, notice that the first letters form a descending sequence by 1, the second letters form an ascending sequence by 3, and the numbers also increase by 3 each time. Only VL12 preserves all three patterns. None of the other options provide the correct combination of letter and number increments.

Why Other Options Are Wrong:
UL12, VM12, and UM12 either have the wrong first letter or the wrong second letter when checked against the identified steps. For example, UL12 has U instead of V, which breaks the minus 1 rule, and UM12 has M instead of L, which breaks the plus 3 rule for the second letters. The none of these option is incorrect because VL12 fits the pattern perfectly.

Common Pitfalls:
Candidates sometimes identify the numerical pattern correctly but guess the letters. Others may focus on one of the letter positions and ignore the second, leading to partially correct but ultimately wrong choices. Properly handling each subsequence separately and then recombining them is the best method.

Final Answer:
The correct next term in the series is VL12.