Question

The third proportional to 9 and 12 is ?
A) 14
B) 16
C) 18
D) 20

Answer 1

Answer:

We have to find the third number.

x= 12:18::18:x

18*18=12*X

324= 12*x

therefore 324/12=27

12*27=324=18*18

formula= product of extremes = product of means

mean= 18,18 that are on the inner side

extreme= 12,27 that are on the extreme ends