Percentage

·       Percentage is a method of representing any quantity in fraction of 100 i.e. out of 100 how much is that quantity.
·       It is often denoted using the percent sign, "%"
·       One percent (1%) means 1 per 100 and 100% means all and so on..

Points to Remember:
·       1/5th of a number = 1/5 ×100 = 20%
·       20% of a mumber = 20/100 = 1/5th of that number.
·       If a number is increased from value A to B then % increase = (B-A)/A × 100
·       If a number is decreased from value A to B then % decrease = (A-B)/A ×100
·         If x% and y% are two successive increase(+ve) or decrease(-ve) in a number then overall  percentage of change = x + y + xy/100
·       If the population of a city increases (+ve) or decreases(-ve) by r%  every year then,
                                                      I.            Population after n year = Present Population ×(1+ r/100)n
                                  II.        Population n years ago = Present Population ×(100/(100+r))n
·       What is the percent value A to B  = A/B × 100
Now let’s understand each of above listed point with examples one by one.

Example:
Calculate 25% of 80
25% =  
25
100

And  
25
 × 80 = 20
100
So 25% of 80 is 20

Example:
A fruit seller had some apples. He sells 40% apples and still has 420 apples. Originally, he had:
Explanation:
Suppose originally he had x apples.
Then, (100 - 40)% of x = 420.
60x = 420
100
 x =420 x 100  = 700.
60





Example:
If the population of a city increases 20% every year and if its present population is 576000. What was the population of city 2 years ago.

Explanation:
This is an example of two successive change.
Population n years ago =Present Population ×(100/(100+r))n

                                    = 576000×(100/(100+20))n

                                     = 400000

Example:
What percentage of 5 is 3

Explanation:
                                     =3/5×100
                                     = 60%
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