Answer:

Step-by-step explanation:
A ratio is a quantified relation between two magnitudes that represent the same proportion.
In this case, those magnitudes are

Where
and
are balls' diameters.
The ratio would be the quotient between them

However, this ratio isn't ratio yet, because it's not based on the same magnitude, we need to transform 9.5 centimeters to millimeters.
We know that 1 centimeter equals 10 milimeter, so, 9.5 centimeters would be

Now, we replace this transformation in the ration, and that would be the answer

If we simplify,
