Ratio nd proportion formula and definition

                         RATIO AND PROPORTION :

Product of means = Product of extremes.

Thus, a : b :: c : d = (b x c) = (a x d)

 

    3.    Fourth Proportional:

If a : b = c : d, then d is called the fourth proportional to a, b, c.

Third Proportional:

a : b = c : d, then c is called the third proportion to a and b.

Mean Proportional:

Mean proportional between a and b is ab.