Question

One ingot contains 10 kg of pure silver and 2 kg of league. What quantity of silver, whose grade is 0.700; is it necessary to melt to obtain silver with a grade of 0.750?

a) 20
b) 22
c) 16
d) 24
e) 19

Answer 1

a) 20

Explanation:

If x is the kg of 0.700 grade silver, then:

Silver in ingot + silver in 0.700 alloy = silver in 0.750 alloy

10 + 0.7x = 0.75(x + 12)

10 + 0.7x = 0.75x + 9

1 = 0.05x

x = 20