3.1 Ratio, Proportions and Variations

3.1(i) Define (a) ratio, (b) proportion and (c) variations (direct and inverse).

(a) Ratio

A relation between two quantities of the same kind (measured in same unit) is called ratio. If $a$ and $b$ are two quantities of the same kind and $b$ is not zero, then the ratio of $a$ and $b$ is written as $a:b$ or in fraction $\frac{a}{b}$$\frac{a}{b}$ e.g., if a hockey team wins 4 games and loses 5, then the ratio of the games won to games lost is $4:5$ or in fraction $\frac{4}{5}$$\frac{4}{5}$