SOLUTION: Doreen Schmidt is a chemist. She needs to prepare 28 ounces of a 12% hydrochloric acid solution. Find the amount of 14% and the amount of 7% solution she should mix to get this sol

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Question 808190: Doreen Schmidt is a chemist. She needs to prepare 28 ounces of a 12% hydrochloric acid solution. Find the amount of 14% and the amount of 7% solution she should mix to get this solution.
Found 2 solutions by richwmiller, mananth:
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
a+b=28,
.14a+.07b=.12(28)
a=20, b=8

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
percent ---------------- quantity
Hydrochloric acid 14.00% ---------------- x ounces
Hydrochloric acid II 7.00% ------ 28 - x ounces
Mixture 12.00% ---------------- 28
Total 28 ounces
14.00% x + 7.00% ( 28 - x ) = 12.00% * 28
14 x + 7 ( 28 - x ) = 336
14 x + 196 - 7 x = 336
14 x - 7 x = 336 - -196
7 x = 140
/ 7
x = 20 ounces 14.00% Hydrochloric acid
8 ounces 7.00% Hydrochloric acid II

m.ananth@hotmail.ca