SOLUTION: During a science experiment, Nico created an 18% alcohol solution by mixing 7 fluid ounces of a 34% alcohol solution with a certain amount of a 4% alcohol solution. How many fluid

Algebra ->  Inequalities -> SOLUTION: During a science experiment, Nico created an 18% alcohol solution by mixing 7 fluid ounces of a 34% alcohol solution with a certain amount of a 4% alcohol solution. How many fluid       Log On


   

Question 1101675: During a science experiment, Nico created an 18% alcohol solution by mixing 7 fluid ounces of a 34% alcohol solution with a certain amount of a 4% alcohol solution. How many fluid ounces of the 18% alcohol solution did he create?
A. 8 fl oz
B. 13 fl oz
C. 15 fl oz
D. 11 fl oz
Found 2 solutions by josgarithmetic, richwmiller:
Answer by josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!
x%2B7 fluid ounces size of the 18% solution

highlight_green%28%2834%2A7%2B4%2Ax%29%2F%28x%2B7%29=18%29

-
34%2A7%2B4x=18%28x%2B7%29
4x%2B34%2A7=18x%2B18%2A7
34%2A7-18%2A7=14x
34-18=2x
2x=16
x=8--------amount of the 4% alcohol used

8%2B7=highlight%2815%29------fluid ounces of solution prepared, 18%

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
Let C denote the 4% solution and D denote the final 18% solution.
We have 7 oz of 34% solution.
Using the method of alligation.
16= 18 - 34
14= 4 - 18
E.g. There are 14 parts of C for every 16 parts of D
then there are 7 parts of z, since (14/16)=7/z
x= 8.0= 7/(14/16) oz of 4% solution to add to your 7 oz of 34% solution.
y= 15.0= (7+8.0) oz of the final 18% solution.
check
0.04 * 8.0 + 0.34 * 7 = 0.18*(7+8.0)
0.32 + 2.38 = 0.18*(15.0)
2.7 = 2.7
ok
34         14       7 oz of 34% solution
      18          15 oz of 18% solution
4         16 16/14*7=8 oz of 4% solution
           30