Theory:

4. Conversion of ratio into percent
 
We can convert ratio into a percentage using the following method.
Example:
(i) \(a:b\)
 
=ab=[ab×100]%
  
(ii) \(3:8\)
 
=38=[38×100]%=3712%
 
5. Conversion of Percent into decimal
To convert the percent to decimal, first change it to a fraction by dividing it by \(1000\) and remove the \(\%\) sign. Then put the decimal point accordingly.
\(a\%\)           \(= a/100\)        \(= 0.0a\)
(percent)     (fraction)       (decimal)
Example:
(i) 25\(\%\)
 
\(=\) 25100
 
\(=\) 0.25\(\%\)
  
(ii) 85\(\%\)
 
\(=\) 85100
 
\(=\) 0.85\(\%\)
  
(iii) 29%
 
\(=\) 29 ·100
 
\(=\) 0.002\(\%\)
6. Conversion of decimal into a Percent
To convert decimal into a percent, first, change it to fraction for the removal of decimal and then multiply it by \(100\) and put the \(\%\) sign.
Example:
(i) 10.9
 
\(=\) 10910 
 
\(=\) [10910×100]%
 
\(=\) 1090\(\%\)
  
(ii) 0.036
 
\(=\) 361000
 
\(=\) 361000 ·100
 
\(=\) 3.6\(\%\)