Ratio is a comparison of two quantities or two numbers or two unites. Even more than two quantities or numbers or unites can be compared and expressed in the form a ratio.


The ratio is written with a colon ( : ).


2 : 3 >>> This is a typical form of writing a ratio. This is read as two to three.


Example : 1


Ravi has 9 pens, 11 pencils, 10 rubbers and 4 erasers.


What is the ratio between the number of pens and pencils?


What is the ratio between the number of pens and erasers?


What is the ratio between the number of pencils and rubbers?


What is the ratio between the number of erasers and rubbers?


The number of pens is 9.


The number of pencils is 11.


The number of rubbers is 10.


The number of erasers is 4.


The ratio between the number of pens and pencils = 9 : 11


The ratio between the number of pens and erasers = 9 : 4


The ratio between the number of pencils and rubbers = 11 : 10


The ratio between the number of erasers and rubbers = 4 : 10


Example : 2


A father has $12,000 with him. He gives away this money to his two sons in the ratio of 2 : 3. How much each son gets from his father?


The amount the father has = $12,000


The ratio in which he gives away this amount to his two sons is = 2 : 3


This implies that the father divides this amount into 5 (= 2 + 3) parts.


So, the each part = 12,000 / 5 = 2,400


The first son gets 2 parts.


2 parts is equal to 2 x 2400 = 4,800.


So, the first son gets $4,800.


The second son gets 3 parts.


3 parts is equal to 3 x 2400 = 7,200


The second son gets $7,200.


The total amount = $4,800 + $7,200 = $12,000







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