Answer:
Geometric mean is the nth root of the product of n numbers
For two numbers it's the square root
for three numbers it's the cube root
for 4 numbers it's the fourth root
etc.
--------------------------
5 and 20
m = √(5 * 20) =
m = √100
m = 10
3 and 12
m = √(3 * 12)
m = √36
m = 6
do the rest the same way