Question

Alloy A contains copper and zinc in the ratio 5 : 2 and alloy B contains copper and zinc in the ratio 3 : 4. Alloy C is prepared by mixing A and B in the ratio 4 : 5. What is ratio of copper to zinc in alloy C is?

1. 5 : 4 
2. 6 : 7 
3. 8 : 9
4. 12 : 13

Answer 1

Correct Answer - Option 1 : 5 : 4 

Given:

Alloy A contains copper and zinc in the ratio 5 : 2

Alloy B contains copper and zinc in the ratio 3 : 4

Alloy C is prepared by mixing A and B in the ratio 4 : 5

Calculations:

Alloy A,

⇒ Copper = 5/7, Zinc = 2/7

Alloy B,

⇒ Copper = 3/7, Zinc = 4/7

A and B taken in the 4 : 5 Ratio

Let A be 4x and B be 5x,

In mixture C,

Copper = (5/7)4x + (3/7)5x  = 35x/7

Zinc = (2/7)4x + (4/7)5x =  28x/7

Ratio of Copper to Zinc in mixture C, 

⇒ 35x/7 : 28x/7

⇒ 5 : 4

∴ Ratio of Copper to Zinc is 5 : 4.