Question

An alloy contains only zinc and copper and they are in the ratio of $7:9$. If the weight of the alloy is $8kg$, then find the weight of copper in the alloy.

Answer 1

Zinc and copper are in the ratio = $7:9$
Let the weight of zonc is $7xkg$ and copper $9xkg$
Total weight = $(7x+9x)kg=16kg$
Total weight of alloy = $8kg$
Now,
$⟹16xkg=8kg⟹x=\frac{8}{16}=\frac{1}{2}=1:2$
So the weight of the copper =$9\times \frac{1}{2}kg=\frac{9}{2}kg=4\frac{1}{2}kg$