Question 460436
Sam has 5 rings each weighing 18g, made of an alloy of 10% silver and 90% gold. He decides to melt down the rings and add enough silver to reduce the gold content to 75%. How much silver should he add?
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let x=grams of silver to add
18*10%=1.8g = initial grams of silver in alloy
18*90%=16.2g=initial grams of gold in alloy
1.8+x=total grams of silver in new alloy
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ratio of silver to gold in new alloy=25/75=1/3=(1.8+x)/(16.2)
3(1.8+x)=16.2
5.4+3x=16.2
3x=16.2-5.4=10.8
x=10.8/3=3.6 g
ans:
The amount of silver to add to reduce the gold content to 75%=3.6g