We can solve this by using the equation:
V=4/3πr^3
So we know the diameter is 15, so the radius is half of that or 7.5 cm.
Now we plug in the values:
V=4/3 * 3.14 * 7.5^3
And solve:
V=1766.25
So the volume of the sphere is 1766.25 cm^3.
I hope this helps!