Question

An alloy consists of nickel, zinc, and copper in the ratio 2:7:9. How many pounds of nickel have to be used to create alloy that contains 4.9 lb of zinc?

Answer 1

We are given ratio nickel to zinc to copper = 2:7:9.

From this ratio we can see that ratio of nickel to zinc is 2:7.

Let us assume number of pounds of nickel have to be used to create alloy that contains 4.9 lb of zinc is x pounds.

So, we can setup a proportion as :

x : 4.9 =  2:7

Or

$\frac{x}{4.9}=\frac{2}{7}$

On cross multiplication, we get

7x= 4.9× 2

7x = 9.8

Dividing both sides by 7, we get

x = 1.4.

Therefore, 1.4 pounds of nickel have to be used to create alloy that contains 4.9 lb of zinc.