We have no dimensions to work with. I'll pick some and try and comply with the conditions of the problem.
Suppose you have an object that is 14 by 22 by 27 cm. These three numbers have no common factor so they cannot be reduced any further, which is helpful for this problem.
Find the Volume
Volume
l = 27 cm
w = 14 cm
h = 22 cm
V = 27 *14 * 22
V = 8316 cm^3
Find the surface area
SA = 2*l*w + 2*l*h + 2*w*h
SA = 2*27*14 + 2*27*22 + 2*14*22
SA = 756 + 1188 + 616
SA = 2558
Just looking at these numbers The surface area is about 1/3 of the volume. I don't think this is always true.
Another way to do this is to consider a cube which might give you a more useful result.
s = L = W = H all three dimensions are equal in a cube.
The volume of a cube is s*s*s = s^3
The surface area of a cube is 2*s*s + 2*s*s + 2s*s = 6s^2


That means whatever the side length, the Surface Area to volume = 6/the side length which is kind of an interesting result.
To find the mean you add all the numbers then divide the sum by how many numbers there are :
1)Ford School
21+19+20=60
there are 3 numbers in the equation so you divide 60 by 3 :
60÷3=20
the mean for Ford School is 20
2)Carter School
41+36+37=114
there are 3 numbers in the equation so you divide 114 by 3 :
114÷3=38
the mean for Carter School is 38
hope this helps