Question

In a metal alloy, the ratio of zinc to copper is 3 to 12. If there are 456 lb of copper, how much zinc is there?

Answer 1

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.

`\begin{gathered} (zinc)/(copper)=(zinc)/(copper) \\ (1)/(4)=(z)/(456) \\ \text{Cross multiply.} \\ 456=4z \\ \text{Divide both sides by 4.} \\ (456)/(4)=(4z)/(4) \\ 114=z \end{gathered}`

Answer: There are 114lb of zinc in a 456lb of copper.