SOLUTION: Alyssa is a chemist with Gemco Pharmaceutical Company. She needs to prepare 12 ounces of a 9% hydrochloric acid solution. The only solutions she currently has available are 4% a

Question 515168: Alyssa is a chemist with Gemco Pharmaceutical Company. She needs to prepare 12 ounces of a 9% hydrochloric acid solution. The only solutions she currently has available are 4% and 12% hydrochloric acid. How much should she use of each solution to obtain the needed solution? Use variables and representation if possible.
Found 2 solutions by josmiceli, lwsshak3:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = ounces of 4% solution needed
Let = ounces of 12% solution needed
given:
(1)
(2)
--------------------------
(2)
(2)
(2)
Multiply both sides of (1) by
and subtract (1) from (2)
(2)
(1)

and, since
(1)
(1)
(1)
4.5 ounces of 4% solution are needed
7.5 ounces of 12% solution are needed
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
Alyssa is a chemist with Gemco Pharmaceutical Company. She needs to prepare 12 ounces of a 9% hydrochloric acid solution. The only solutions she currently has available are 4% and 12% hydrochloric acid. How much should she use of each solution to obtain the needed solution? Use variables and representation if possible.
**
let x=ounces of 4% solution
12-x=ounces of 12% solution
..
4%x+12%(12-x)=9%*12
.04x+1.44-.12x=.09*12
-.08x=-.36
x=.36/.08
4=4.5 ounces
ans:
Alyssa should use of each of the following solutions to obtain the needed solution
4.5 ounces of 4% solution
and
7.5 ounces of 12% solution
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