An alloy of copper and nickel contains 65% copper. A second alloy contains copper and nickel in the ratio 17 : 3. In what ratio should the two alloys be mixed so that the new mixture contains 4 times as much copper as nickel?

Question: An alloy of copper and nickel contains 65% copper. A second alloy contains copper and nickel in the ratio 17 : 3. In what ratio should the two alloys be mixed so that the new mixture contains 4 times as much copper as nickel?

Solution:
First alloy - 65% copper. ∴ 35% Nickel.
Ratio is 65 : 35 = 13 : 7.

2nd alloy,
Ratio is 17 : 3
∴ Proportion of copper in the 1st alloy = 13/20 and
proportion of copper in the 2nd alloy = 17/20.
Also proportion of copper in resulting alloy = 4/5.

Hence required ratio is (17/20 - 4/5) : (4/5 – 13/20) = 1 : 3.