Question

The ratio of Copper and Zinc in an alloy is $7:8$. If the weight of zinc is $12.8kg$, find the weight of copper in the alloy?

Answer 1

Let the weight of Copper be $xkg$

Then the ratio between Copper and Zinc in an alloy is $xkg:12.8kg$

It is given that the ratio between Copper and Zinc in an alloy is $7:8$

So, both the ratios must be equal

Then,

$$\begin{gathered} \Rightarrow xkg:12.8kg=7:8 \\ \Rightarrow \frac{x}{12.8}=\frac{7}{8} \\ \Rightarrow x=\frac{7\times 12.8}{8} \\ \Rightarrow x=\frac{89.6}{8} \\ \Rightarrow x=11.2 \end{gathered}$$

Hence, the Weight of Copper be $11.2kg$