SOLUTION: 100 gm of an alloy contains 50% copper, 30% silver and 20% gold. How much of pure copper, silver and gold needs to be added to this mixture to get an alloy with 60% copper, 35% si

Question 1019524: 100 gm of an alloy contains 50% copper, 30% silver and 20% gold.
How much of pure copper, silver and gold needs to be added to this mixture to get an alloy with 60% copper, 35% silver and 5% gold in the resulting alloy.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
100 gm of an alloy contains 50% copper, 30% silver and 20% gold.
How much of pure copper, silver and gold needs to be added to this mixture to get an alloy with 60% copper, 35% silver and 5% gold in the resulting alloy.
:
Since the percent gold is less, no gold needs to be added
Find the total amt of gold
.20(100) = 20 mg
Find the total amt (A) required to reduce the gold to 5%
.05A = 20
A = 400 mg amt of the new alloy
.
Find the amt of copper originally
.50(100) = 50 gm of copper
Find the amt of copper(C) to be added to raise percent to 60%
50 + c = .60(400)
c = 240 - 50
c = 190 mg of copper required
:
Find the amt of silver originally
.30(100) = 30 gm of silver
Find the amt of silver (s) to be added to raise the percent to 35%
30 + s = .35(400)
s = 140 - 30
s = 110 mg of silver required
:
Summarize; add 190 mg of copper, and 110 mg of silver to the 100 mg you have
(Adds up to 400), gold % has been reduced to 5%
:
Check this
Copper: .60(400) = 240; that's 190 mg added plus the original amt of 50mg
Silver: .35(400) = 140; 110 mg added plus 30 mg originally

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