SOLUTION: A metal alloy is a metal made by blending 2 or more types of metal.A jeweler has supplies of two metal alloys. One alloy is 30% gold and the other is 10% gold. How much of each all

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Question 703038: A metal alloy is a metal made by blending 2 or more types of metal.A jeweler has supplies of two metal alloys. One alloy is 30% gold and the other is 10% gold. How much of each alloy should the jeweler combine to create 4 kg of an alloy containing 15% gold?
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Higher concentration and lower concentration available; known quantity of mixture desired.
Key idea is (quantity of gold)/(quantity of mix)=(fraction as gold)

a= quantity of higher concentration alloy to use (unknown)
b= quantity of lower concentration alloy to use (unknown)
P_sub_a = percent gold in a, 0.30
P_sub_b = percent gold in b, 0.10
F = the FRACTION of the desired alloy which is gold. 0.15

%28a%2AP%5Ba%5D%2Bb%2AP%5Bb%5D%29%2F%28a%2Bb%29=F
a%2Bb=4
Two equations and two unknowns. Solve for a and b.