<PRE><B>Question 519949</B>


Pure Silver
Amount = x grams
Concentration = 1 (Pure Silver)

Alloy
Amount = 30 grams
Concentration = 50% = 0.5

Final Alloy
Amount = 30+x grams
Concentration = 60% = 0.6

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Pure Sliver Amount * Concentration + Alloy Amount * Concentration = Final Alloy * Final Alloy Concentration

x*1 + 30*0.5 = (30+x)*0.6
x+15=18+0.6x
x-0.6x=18-15
0.4x=3
x=3/0.4
x=7.5 grams

7.5 grams of pure silver must be added to 30 grams of an alloy that is 50% silver to obtain 37.5 grams of an alloy that is 60% silver?
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