How to calculate Percentage

In mathematics, a percentage is a way of expressing a number as a fraction of 100 (per cent meaning "per hundred"). It is often denoted using the percent sign, "%", or the acronym "pct". For example, 45% (read as "forty-five percent") is equal to 45 / 100, or 0.45.We can even use fraction calculator to find it.

Percentages are used to express how large/small one quantity is, relative to another quantity. The first quantity usually represents a part of, or a change in, the second quantity, which should be greater than zero. For example, an increase of $ 0.15 on a price of $ 2.50 is an increase by a fraction of 0.15 / 2.50 = 0.06. Expressed as a percentage, this is therefore a 6% increase.

Although calculating percentages are usually used to express numbers between zero and one, any dimensionless proportionality can be expressed as a percentage. For instance, 111% is 1.11 and -0.35% is -0.0035.

Question:-

How many kilograms of salt must be added to 12 kg of an 8% salt solution to make a solution that is 20% salt

Answer:-

Let's see how to find percentage

        original          added        result

           
Salt         x                12         ( 12+x ) 


%           100%              8%           20%

100% x is added to 8% (12)to make 20% of ( 12+x )

8%(12)+100% of x = 20%(12+x)

0.96+x = 2.4 +0.2x

0.8x = 1.44

So x = 1.8 grams

Salt to be added = 1.8 grams