SOLUTION: A goldsmith has two alloys that are different purities of gold. The first is three-fourths pure gold and the second is five-twelfths pure gold. How many ounces of each should be

Algebra ->  Customizable Word Problem Solvers  -> Mixtures -> SOLUTION: A goldsmith has two alloys that are different purities of gold. The first is three-fourths pure gold and the second is five-twelfths pure gold. How many ounces of each should be       Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 243473: A goldsmith has two alloys that are different purities of gold. The first is three-fourths pure gold and the second is five-twelfths pure gold. How many ounces of each should be melted and mixed in order to obtain a 6-oz mixture that is two-thirds pure gold?
I am having problems with the fraction part... Hope you can help
Thanks
Lisa

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A goldsmith has two alloys that are different purities of gold. The first is three-fourths pure gold and the second is five-twelfths pure gold. How many ounces of each should be melted and mixed in order to obtain a 6-oz mixture that is two-thirds pure gold?
---
Equation:
gold + gold = gold
(3/4)x + (5/12)(12-x) = (2/3)12
Multiply thru by 12 to get:
9x + 5*12- 5x = 8*12
4x = 3^12
x = 9 oz (amt. of (3/4) alloy needed in the mix)
----------------
12 - x = 12-9 = 3 oz (amt of (5/12) alloy needed in the mix)
=======================================
Cheers,
Stan H.