SOLUTION: a lot of brass scrap weighing 350 kg contains 30% zinc. how many kg of zinc must be added in melting to raise the percentage of zinc to 40%?

Question 850090: a lot of brass scrap weighing 350 kg contains 30% zinc. how many kg of zinc must be added in melting to raise the percentage of zinc to 40%?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
a lot of brass scrap weighing 350 kg contains 30% zinc.
how many kg of zinc must be added in melting to raise the percentage of zinc to 40%?
:
let z = amt of zinc required to do this
:
A typical mixture equation
.30(350) + z = .40(x+350)
105 + z = .4z + 140
z - .4z = 140 - 105
.6z = 35
z = 35/.6
z = 58kg of zinc required
:
:
Check this
.30(350) + 58.333 = .4(58.33+350)
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