Derrick M.

asked • 08/16/17

Word Problem

How many gallons of a90% antifreeze solution must be mixed with 6060 gallons of 20% antifreeze to get a mixture that is 80% antifreeze? Use the six-step method.

3 Answers By Expert Tutors

By:

Andrew M. answered • 08/17/17

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Mathematics - Algebra a Specialty / F.I.T. Grad - B.S. w/Honors

Arturo O. answered • 08/16/17

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Andrew M.

The total was not 60 gallons.
We added 60 gallons of 20% solution to an unknown
amount of 90% solution to get (60+x) gallons of 80%
solution.
.9x + .2(60) = .8(x+60)
 
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08/17/17

Arturo O.

Thanks Andrew. I see that I misread the problem statement.
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08/17/17

Andrew M.

No problem.  Lord knows I've done that enough times.
 
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08/17/17

Arturo O.

Yes, and we will do it many more times!  It is frustrating, but we must press on and help our future engineers and scientists.
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08/17/17

Arturo O.

Michael,
 
If 6060 is the total number of gallons (assuming no typo in the problem statement) and x is gallons of the 90%, then shouldn't the first equation be
 
0.90x + 0.20(6060 - x) = 0.80(6060) ?
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08/16/17

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