Given data:
1. zinc to copper ratio = 3:12 or 1:4 in simplest form. This means, in every 1lb of zinc, there are 4lb of copper.
2. 456lb of copper
Find: amount of zinc in lb
Solution:
We can use direct proportion here in which zinc/copper = zinc/copper.
[tex]\begin{gathered} \frac{zinc}{copper}=\frac{zinc}{copper} \\ \frac{1}{4}=\frac{z}{456} \\ \text{Cross multiply.} \\ 456=4z \\ \text{Divide both sides by 4.} \\ \frac{456}{4}=\frac{4z}{4} \\ 114=z \end{gathered}[/tex]Answer: There are 114lb of zinc in a 456lb of copper.
