Question

The ratio of weights of zinc and copper in an alloy is 5 : 8. If the weight of copper in a sample of this alloy is 12 g, what is the weight of zinc?

• A. 6.5 g
• B. 6 g
• C. 7.5 g
• D. 7 g

Answer 1

The correct option is C 7.5 g

Given:
Ratio of weight of zinc and copper $=5:8$
Let the weight of zinc for $8\text{g}$ of copper be $x$.
Using the concept of equivalent ratios,
$\frac{Zinc}{Copper}$ $=\frac{5}{8}$ $=\frac{x}{12}$
<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> ⇒ $x$ $=\frac{5\times 12}{8}$
⇒ $x$ $=7.5\text{g}$
$\therefore$ The weight of zinc is $7.5\text{g}$.