If all the letters in the word 'REGULATORY', are arranged according to English alphabetical order, the positions of how many letters will remain unchanged after rearrangement?

Let's write the original word and line it up with its alphabetically sorted version:
* Original: R E G U L A T O R Y
* Sorted: A E G L O R R T U Y

Let's compare the positions:

1. R $\to$ A (Changed)
2. E $\to$ E (Unchanged)
3. G $\to$ G (Unchanged)
4. U $\to$ L (Changed)
5. L $\to$ O (Changed)
6. A $\to$ R (Changed)
7. T $\to$ R (Changed)
8. O $\to$ T (Changed)
9. R $\to$ U (Changed)
10. Y $\to$ Y (Unchanged)

There are exactly 3 letters (E, G, Y) whose positions remain unchanged.