What is Proportion ?
When Two Ratios are equal then we say that they are in Proportion and use the symbol “: :” or “=” to equate two ratios.
Four Numbers in Proportion
Let a, b, c, d are four numbers said to be in proportion.
then, a : b = c : d or a : b :: c : d
here a and d are called the extreme terms or extremes.
b and c are called the middle terms or means.
When Four numbers are in proportion
then, Product of extremes = Product of means.
i.e, In proportion a : b :: c : d,
(a x d) = (b x c)