Question

A metal worker has several 1-kilogram bars of a metal alloy that contain 23% copper and several 1-kilogram bars that contain 79% copper. How many bars of each type of alloy should be melted and combined to create 48 kilograms of a 44% copper alloy?

Answer 1

30 each of 23% bars and 18 each of 79% bars

Explanation:

If x is the number of 1 kg 23% copper bars, and y is the number of 1 kg 79% copper bars, then:

x + y = 48

0.23x + 0.79y = 0.44(48)

Substituting and solving:

0.23x + 0.79(48-x) = 0.44(48)

0.23x + 37.92 - 0.79x = 21.12

16.8 = 0.56x

x = 30

y = 48 - x

y = 18

You need 30 each of 23% bars and 18 each of 79% bars.