The surface area of a sphere is

where r is the radius;
The circumference is

so that

using this value we can evaluate the surface area of 1 ball as:

For 100 ball you get:
Answer:
7 miles per gallon
Step-by-step explanation:
since 3/4 or 75% ARE black, 1/4 will not be black. 1/4=.25 which is 25%.