Question

An alloy contains copper and zinc in the ratio 7:3 . If it contains 12.6 g of copper , how much does this alloy weigh ?

Answer 1

Let the amounts of copper and zinc in the alloy be 7x and 3x respectively. (Since ratio given is 7:3)
Total weight of the alloy = Weight of Copper + Weight of Zinc
= 7x + 3x
=10x -----------(1)

Given that Weight of Copper = 12.6 g
=> 7x = 12.6 g
=> x = 12.6 / 7
= 1.8 g

From (1) total weight of the alloy = 10x
= 10 * 1.8
= 18 g

Hence the alloy weighs 18 grams.

Hope this helps :)