Question

The ratio of zinc to copper in an alloy is 2 : 5 . Find the quantity of copper in 4.2kg of the alloy.

Answer 1

Answer: The answer is 3 kg.

Step-by-step explanation:  Given that there is 4.2 kg of an alloy. The alloy contains zinc and copper in the ratio 2 : 5.

We are to find the quantity of copper in the alloy.

Let, '2x' and '5x' be the quantities of zinc and copper respectively in the alloy. Then, we have

$2x+5x=4.2\\\\\Rightarrow 7x=4.2\\\\\Rightarrow x=0.6.$

Therefore, the quantity of copper in the alloy is

= 5 × 0.6

= 3.

Thus, the required quantity is 3 kg.

Answer 2

Answer:

3kg

Step-by-step explanation:

Amount of copper in alloy= 5x

Amount of zinc in the alloy= 2x

(because of the ratio 2:5)

Given weight of alloy= 4.2kg

⇒2x + 5x= 4.2 kg

  7x= 4.2kg

x= 4.2 ÷ 7

x= 0.6

∴ Amount of copper in alloy= 5x= 5×0.6 = 3kg