The positions of how many letters in the word PANTRY will remain unchanged when the letters within the word are arranged alphabetically?

Let's compare the original positions of the letters in the word PANTRY with their positions when arranged in alphabetical order:
* Original Word:
1. P
2. A
3. N
4. T
5. R
6. Y

* Alphabetical Arrangement:
1. A
2. N
3. P
4. R
5. T
6. Y

Comparing them position by position:

* P $\to$ A (Changed)
* A $\to$ N (Changed)
* N $\to$ P (Changed)
* T $\to$ R (Changed)
* R $\to$ T (Changed)
* Y $\to$ Y (Unchanged)

Only 1 letter ('Y') remains unchanged in its position.