First, let's notice that we're dealing with a hemisphere, which is really HALF of a sphere.
Formula for volume of a sphere: VS = (4/3) * π*r3 where r is the radius of the sphere
So the volume of a hemisphere will be HALF the volume of a sphere: VH = (1/2) * (4/3) * π*r3
You're given the diameter of the sphere d = 7.6 m, so radius is HALF the diameter: r = (1/2) * 7.6 = 3.8 m
Plug it in formula for VH: VH = (1/2) * (4/3) * π * 3.83 = 112.92364805 cubic meters
Round to nearest tenth ----> VH = 112.9 cubic meters