Question

If 140 g brass is mixed with copper to prepare an alloy having brass and copper in the ratio 4 : 3, then how much copper has been taken to prepare the alloy?
1. 245 g
2. 105 g
3. 60 g
4. 80 g

Answer 1

Correct Answer - Option 2 : 105 g

Given:

Quantity of brass mixed with copper = 140 g

Desired ratio of brass and copper = 4 : 3 

Calculation:

Let the quantity of brass and copper be 4a and 3a respectively. 

4a = 140g 

⇒ a = 140/4 g 

⇒ a = 35 g

∴ The quantity taken of copper to prepare the alloy = 3a = 3 × 35 

⇒ 105 g