Question

In two alloys, copper and zinc are related in the ratio of 4 : 1 and 1 : 3 10 kg of 1st alloy, 16 kg of 2nd alloy and some of pure copper are melted together An alloy was obtained in which the ratio of copper to zinc was 3 : 2 Find the weight of the new alloy?

• A. 35 kg
• B. 45 kg
• C. 40 kg
• D. 50 kg

Answer 1

The correct option is A 35 kg

In 10 kg of 1st alloy the ratio of copper and zinc = 4:1
$\therefore$ Copper $=\frac{4}{5}\times 10kg=8kg$ Zinc $=\frac{1}{5}\times 10kg=2kg$ In 16 kg of 2nd alloy the ratio of copper and zinc = 1:3
$\therefore$ Copper $=\frac{1}{4}\times 16kg=4kg$ Zinc $=\frac{3}{4}\times 16kg=12kg$
Let x kg be the amount of pure copper added Given Copper : Zinc = 3 : 2 in the new alloy, i.e. (8 + 4 + x) : (2 + 12) = 3 : 2
$\Rightarrow \frac{12+x}{14}=\frac{3}{2}\Rightarrow 24+2x=42\Rightarrow 2x=18\Rightarrow x=9kg$
$\therefore$ Weight of the new alloy = (8 + 4 + 9 + 2 + 12) = 35 kg