Answer:
The volume of the softball is 6.6 times the volume of the tennis ball
Explanation:
we know that
The volume of a sphere is equal to

step 1
Find the volume of the softball
we have

substitute

step 2
Find the volume of the tennis ball
we have

substitute

step 3
Divide the volume of the softball by the volume of the tennis ball

therefore
The volume of the softball is 6.6 times the volume of the tennis ball
Alternative Method
we know that
If two figures are similar, then the ratio of its volumes is equal to the scale factor elevated to the cube
The scale factor is equal to the ratio of its radius

therefore
The scale factor elevated to the cube is

therefore
The volume of the softball is 6.6 times the volume of the tennis ball