To determine the number of ways to dress up the 5 mannequins with the 8 new dresses, we'll consider that each mannequin can wear any of the 8 dresses. Since the dresses can be reused (the same dress can be used on multiple mannequins), we can use the counting principle for each mannequin.
Here's the step-by-step calculation:
- Choices for the First Mannequin: There are 8 dresses available, so there are 8 choices.
- Choices for the Second Mannequin: Again, there are 8 choices.
- Choices for the Third Mannequin: Also 8 choices.
- Choices for the Fourth Mannequin: Still, there are 8 choices.
- Choices for the Fifth Mannequin: Finally, there are 8 choices here as well.
Since the choices for each mannequin are independent, we multiply the number of choices together:
\[ \text{Total Ways} = 8 \times 8 \times 8 \times 8 \times 8 = 8^5 \]
Now, we calculate \( 8^5 \):
\[ 8^5 = 32768 \]
Thus, the total number of ways the dress-shop owner can dress the 5 mannequins is:
\[ \boxed{32768} \]