Question

find the mean proportion between 9 and 81

Answer 1

a= 9
c= 81
b=?
a:b=b:c
9:b=b:81
${b}^{2} = 729$
$b = \sqrt{729}$
b=27.

So, the mean proportion=27.

Hope it helps you!!!

Answer 2

a-9
c-81
b-?
a:b::b:c
=9:b::b:81
=9:b=b/81
b^2=729
b=27