Math Concentration

posted by .

Joe has a ring weighing 10 grams made of an alloy of 13% silver and the rest gold. He decides to melt down the rings and add enough silver to reduce the gold content to 69%. How many grams of silver should he add?

My set up is:

10 (.13 + .87) = 10 (.13 + X + .69)

I'm not sure if that's correct.

  • Math Concentration -

    Silver = 0.13 * 10 = 1.3 grams.

    Gold = 10 1.3 = 8.7 grams.

    New Alloy: Gold=69% of total solution.

    G / (G+S) = 0.69,
    8.7 / (8.7 + S) = 0.69,
    Cross multiply:
    6 + 0.69S = 8.7,
    0.69S = 8.7 - 6 = 2.7,
    S = 3.91 Grams of silver, total.
    3.91 - 1.3 = 2.6 grams of silver added.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. chemistry

    silver has density of 10.5 g/cm3 and gold has a density of 193.g/cm3 which liquid is denser silver and gold are liquids?
  2. algebra

    a jeweler purchased 5 oz of a gold alloy and 20 oz of a silver alloy for a total cost of $540. The next day at the same price per ounce, the jeweler purchased 4 oz of th egold alloy and 25 oz of the silver alloy for a total cost of …
  3. chemistry

    Archimedes used density along with mass and volume of alloys (mixtures) of gold and silver to determine the percent of gold (and also silver) in these alloys by simple, non-destructive measurements. Prove that the mass of gold in a …
  4. algebra

    Joe has a ring weighing 15 grams made of an alloy of 20 silver and the rest gold. He decides to melt down the rings and add enough silver to reduce the gold content to 67 . How many grams of silver should he add?
  5. Chemistry

    A piece of metal alloy (a solution of metals) is made of gold and silver. It is 20% by mass silver. An irregularly shaped piece of this alloy contains 0.356 lb of gold. When the alloy is added to a graduated cylinder that contains …
  6. Physics(class) /Math (problem)

    Joe has a ring weighing 16 grams made of an alloy of 20% silver and the rest gold. He decides to melt down the rings and add enough silver to reduce the gold content to 69% . How many grams of silver should he add?
  7. algebra

    A chemist has x grams of an alloy that is 20% silver and 10% gold, and y grams of an alloy that is 25% silver and 30% gold. Express the number of grams of gold in the two allows in terms of x and y.
  8. Math

    The amounts by weight of gold, silver and lead in three alloys of these metals are in the ratio 1:5:3 in the first alloy, 2:3:4 in the second and 5:2:2 in the third. How many kg of the first alloy must be used to obtain 10kg of an …
  9. Chemistry 101

    A crown is determine to weigh 2.65 kg. When this crown is submerged in a full basin of water, the overflow is found to be 145 mL. Is the crown pure gold or a gold-silver alloy?
  10. Chemistry 101

    A crown is determine to weigh 2.65 kg. When this crown is submerged in a full basin of water, the overflow is found to be 145 mL. Is the crown pure gold or a gold-silver alloy?

More Similar Questions