In the following mixed arrangement BM%R#J@K!DF69L4*15NEP23AYQZ#7UG, which character is positioned sixth to the left of the twentieth character from the left end of the arrangement?

Introduction / Context:
This is a positional reasoning question involving a mixed sequence of letters, digits and symbols. The arrangement BM%R#J@K!DF69L4*15NEP23AYQZ#7UG is given and we need to locate a character that is defined by a two step positional description. These questions test your ability to manage counting operations accurately while handling complex strings.

Given Data / Assumptions:

The sequence from left to right is BM%R#J@K!DF69L4*15NEP23AYQZ#7UG.
We number positions from the left starting at 1.
The twentieth character from the left must be found first.
From that twentieth character, we then move six positions to the left and identify the character there.

Concept / Approach:
The key steps are counting carefully and avoiding misalignment. First, assign a position number to each character. Once we identify the twentieth character, we subtract six from its position index to get the target position. We then check which character sits in that target position. This method ensures we follow the positional instruction precisely and do not get confused by the variety of characters in the string.

Step-by-Step Solution:

Verification / Alternative check:
To verify, you can recount the positions, perhaps grouping them in sets of five for easier counting. Make sure that position 20 is indeed E by counting again from the start. Then move exactly six steps back, counting 1 for 19, 2 for 18, and so on until you reach the sixth step at position 14. In every recount, position 14 remains L, confirming that our positional arithmetic and reading of the sequence are both accurate.

Why Other Options Are Wrong:

K is at position 8, which is not the required target position and is far away from the twentieth character when we move six to the left.

4 sits at position 15, just one place to the right of the correct position, which indicates a typical off by one counting error if chosen.

9 is at position 13, which is close but not the exact sixth position to the left of the twentieth character, again signifying miscounting.

Common Pitfalls:
One of the most common errors is miscounting positions, especially when the string has many characters and includes symbols. Another issue is confusing left and right after identifying the reference position. It is helpful to write down the positions clearly and to move step by step, marking positions as you move to avoid losing track. Clear notation greatly reduces mistakes in these positional reasoning questions.

Final Answer:
The character that is sixth to the left of the twentieth from the left end in the given arrangement is L.