Question 433981
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The ratio in which the two alcohol solutions must be mixed is exactly determined by where the 20% of the mixture lies between the 15% and 28% of the two ingredients.<br>
The difference between 15 and 20 is 5; the difference between 20 and 28 is 8.<br>
So the two ingredients must be mixed in the ratio 5:8.  Note that since 20% is closer to 15% than it is to 28%, the larger portion must be the 15% alcohol solution.<br>
Solve the problem using a proportion, given that we are using 10 gallons of the 15% alcohol.<br>
{{{5:8=x:10}}}
{{{8x=50}}}
{{{x=50/8=6.25}}}<br>
ANSWERS:
(1) 6.25 gallons of the 28% alcohol should be used
(2) the mixture will be 10+6.25 = 16.25 gallons<br>