Word problem

Question

Gold used to make jewerly is often a blend of gold, silver, and copper. Consider three alloys of these metals. The first alloy is 75% gold, 5% silver, and 20% copper. The second alloy is 75% gold, 12.5% silver, and 12.5% copper. The third alloy is 37.5% gold and 62.5% silver. If 100 g of the first alloy costs $2120.80, 100 g of the second alloy costsnbsp $ 2150.50, and 100 g of the third alloy costs $ 1300.00, how much does each metal cost?
Gold costs $
nothing/g. (Round to the nearest cent as needed.)

Answer 1

 

   G is the price of the gold

   S is the price of the silver

   C is the price of the copper

 

Since these percentages are of 100 grams each, their

weights can be taken as is.

 

  75G + 5S + 20C = 2120.82

  75G + 12.5S + 12.5C = 2150.50

  37.5G + 62.5S  = 1300

  

 

Using technology to solve this system, the solutions are

 

G=28, S=4 and C=0.04