# Ratio and Proportion - Quantitative Aptitude

## Ratio

Ratio is a relation between two quantities or numbers. A ratio of a and b is denoted by a:b

## Proportion

Proportion is a statement that two ratios are equal. When two ratios are equal, the four terms involved, taken in order are called proportional, and they are said to be in proportion. a/b = c/d
Continued Proportion
Three quantities are said to be in continued proportion, if the ratio of the first to the second is same as the ratio of the second to the third. a/b = b/c; b is called mean proportion.
Compounded Ratio of two ratios a/b and c/d is ac/bd or ac : bd.
Invertendo: If a : b :: c : d then b : a :: d : c
Alternendo: If a : b :: c : d then a : c :: b : d
Componendo: If a : b :: c : d then (a +b) : b :: (c +d) : d
Dividendo: If a : b :: c : d then (a - b) : b :: (c - d) : d
Componendo and Dividendo: If a : b :: c : d then (a +b) : (a - b) :: (c +d) : (c - d)

Here is an introduction to Ratio and Proportion. You can subscribe to our Youtube channel for more videos and short-cut techniques

How do we apply all the concepts of Ratio and proportion to the problems. Here are some of the short-cut and easy way to do problems from Ratio and Proportion.