Question

how to find out third proportional to 9 and 12

Answer 1

a/b=b/c
9/12=12/x
x=16

Answer 2

Let the third proportion be x

The third proportion is the mean proportion

9:x::x:12

Product of means= Product of extremes

x×x= 9×12

x^2= 108

x= root of 108

x= 10.39

Please verify answer!