Arithmatic: Percentage

Hi aspirants,

       In this post we came with the most important topic of mathematics, which rules most of the problems of any competitive exam, that is percentages.


Because in bank exams or any other competitive you can see percentages as common thing even in data interpretation and more. So why to wait lets start with percentages now.

First we see the formula's then we go through some examples.

Formula's/ Rules:
1. If A is x% more than B, then B is what % less than A? (Or)
If value is increased by x%, to restore it to the former value the new value must be decreased by what %?

Decrease%  =  (x)*100/(100+x)

2. If A is x% less than B, then B is what % more than A? (Or)
If a value is decreased by x%, to restore it to the former value the new value must be increased by what %?

Increase%  = (x*100)/(100-x)

3. If a value is first increased by x%, and then the value is decreased by x% in this change the total change of value is always decrease.

Decrease%  = (x*x)/100%
(Or)
Decrease%  = (x*x)/(100*100)

( % means 1/100)

4. If there are two variables (x,y) and are related to each other, the first is increased by x%, the other one decreased by y%. In this transaction the net change is

Net change = (100+x)(100-y)/100

(If the result is positive then the change is increase, if result is negative then the change is decrease)

We can use formula 4 for both the cases x increase or decrease and y increase or decrease but both the two must always be opposite. That is if x is increase then y must decrease or if x is decrease then y must increase in these cases the above formula works.

5. In some cases we get problems like, if a person get some x salary and spent A amount and spent B amount of remaining amount, he left with y(amount value) then what is x value? To solve these type of questions we have below formula.

Salary or past value (x) = y *(100/(100-A))*(100/(100-B)) etc..
Means if how many remainings come that many increases at end in place of A and B etc..,

In next update we are going to give examples for the above formula's along with some shortcuts to crack the competetive exams..


Keep visiting for next update.......