Final answer:
The acceleration on the rough ice is approximately -6.74 m/s².
Step-by-step explanation:
To calculate the acceleration on the rough ice, we can use the formula:

Where:
a is the acceleration
is the final velocity (6.5 m/s)
is the initial velocity (8.9 m/s)
t is the time taken to slow down
The skater's steady slowing is assumed to be constant, allowing us to rearrange the formula to solve for acceleration.

a = (6.5 - 8.9) / t
The skater's velocity decreases from 8.9 m/s to 6.5 m/s over 5.3 m due to frictionless rough ice, indicating no external forces, as per the equation.

Where:
a is the acceleration
is the final velocity (6.5 m/s)
is the initial velocity (8.9 m/s)
d is the distance (5.3 m)

We determine the acceleration on the rough ice to be roughly -6.74 m/s² by evaluating this equation.