1) Ratio → A ratio is simply a fraction that is expressed as "x : y" and read as "ratio of x is to y".
2) Proportion → The equality of two ratios on fractions is called proportion.
Expression ⇒ a : b : : c : d or a : b = c : d
Which implied (b × c) = (a × d)
2.1) Fourth proportional → If a : b : : c : d then d is called fourth proportion calculated as d =
2.2) Third proportional → If a : b : : b : c then c is called third proportional.
2.3) Mean proportional → If a : b : : b : c then b is called mean proportional.
2.4) Compounded ratio → If three ratios are given as (a : b) (c : d) (e : f).
The compound ratio is ⇒ (ace : bdf)
2.5) Table for various ratios
2.6) Variations → If 'x' is directly proportional to 'y' then x = ky.
Where is constant.
2.7) If sides of any two figure are in the ratio a : b then,
ratio of their areas = a2 : b2
ratio of their volumes = a3 : b3