SOLUTION: Mixture Problem: A jeweler has five rings, each weighing 18g, made of an alloy of 10% silver and 90% gold. She decides to melt down the rings and add enough silver to reduce the

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Question 775461: Mixture Problem: A jeweler has five rings, each weighing 18g, made of an alloy of 10% silver and 90% gold. She decides to melt down the rings and add enough silver to reduce the gold content to 75%. How much silver should she add?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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A jeweler has five rings, each weighing 18g, made of an alloy of 10% silver and 90% gold.
She decides to melt down the rings and add enough silver to reduce the gold content to 75%.
How much silver should she add?
:
5 * 18 = 90 grams total weight
Let s = amt of pure silver to be added
:
Write the equation in terms of silver, results will be 25% silver (and 75% gold).
.10(90) + s = .25(s+90)
9 + s = .25s + 22.5
s - .25s = 22.5 - 9
.75s = 13.5
s = 13.5/.75
s = 18 grams of silver to be added