1. Summary

Ratios are used to compare quantities.  Ratios help us to compare quantities and determine the relation between them.  We write ratios in the form of fractions, and then compare them by converting them into like fractions.  If these like fractions are equal, then we say that the given ratios are equivalent. 

Eg:6 pens cost Rs 90.  What would be the cost 10 such pens? 
Solution:
Cost of 6 pens :Rs 90
Cost of 1 pen = 90/6=Rs 15
Hence, cost of 10 pens =10×15=150

The ratio of two quantities in the same unit is a fraction that shows how many times one quantity is greater or smaller than the other. When two ratios are equivalent, the four quantities are said to be in proportion.

Ratio and proportion problems can be solved by using two methods, the unitary method and equating the ratios to make proportions, and then solving the equation. 

Percentages:

Percentage is another method used to compare quantities. Percentages are numerators of fractions with the denominator 100. 

Eg:

Meaning of percentage: 

Per cent is derived from the Latin word ‘per centum’, which means per hundred
Per cent is represented by the symbol - %.

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