SOLUTION: How much pure disinfectant must be added to 30 gallons of an 8% solution to increase its strength of 25%?

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Question 1081001: How much pure disinfectant must be added to 30 gallons of an 8% solution to increase its strength of 25%?

Answer by ikleyn(52787)   (Show Source): You can put this solution on YOUR website!
.
How much pure disinfectant must be added to 30 gallons of an 8% solution to increase its strength to 25%?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

Let x be the volume of the pure disinfectant under the question, in gallons.

Then the volume of the new mixture will be (30 + x) and the volume content of the pure disinfectant in the new mixture 
     will be 0.08*30 + x gallons.


So, the concentration equation is

 = 0.25.

Simplify and solve it for x:

2.4 + x = 0.25*(30+x),

2.4 + x = 7.5 + 0.25x,

x - 0.25x = 7.5 - 2.4,

0.75x = 5.1  ---->  x =  = 6.8.


Answer.  6.8 gallons of the pure disinfectant must be added.

There is entire bunch of lessons covering various types of mixture problems
    - Mixture problems
    - More Mixture problems
    - Solving typical word problems on mixtures for solutions
    - Word problems on mixtures for antifreeze solutions
    - Word problems on mixtures for alloys
    - Typical word problems on mixtures from the archive
in this site.

Read them and become an expert in solution the mixture word problems.

Also, you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this textbook in the section "Word problems" under the topic "Mixture problems".



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