Hi Lenora W.
You can use the formula for the Volume of a Sphere, since a Hemisphere is half of a sphere. Like the radius is half of the diameter. Check this formula Volume of a sphere is
(4/3)∏*(radius)3
A Hemisphere would be half of this
(4/3)∏*(raduis)3 * 1/2
Can you continue by looking up the formulas to make sure they are correct then just plug in your numbers.
To get you started, I will do the radius, since it is half the diameter then
52.9 * 1/2 = 26.45 is your radius.
I hope this helps you to finish up.