.
Let w be the unknown volume of water to add, in liters.
Then the volume of the 15% solution to use is (3-w) liters.
Your equation is
pure alcohol + pure alcohol = total pure alcohol
0.15*(3-w) + 0 = 0.1*3, or
0.45 - 0.15w = 0.3
0.45 - 0.3 = 0.15w
0.15 = 0.15w ====> w = = 1 liter.
Answer. 1 liter of water and 2 liters of the original 15% alcohol solution is required.
Solved.
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It is a standard and typical mixture problem.
For introductory lessons covering various types of mixture word problems see
- Mixture problems
- More Mixture problems
- Solving typical word problems on mixtures for solutions
- Typical word problems on mixtures from the archive
in this site.
You will find there ALL TYPICAL mixture problems with different methods of solutions,
explained at different levels of detalization, from very detailed to very short.
Read them and become an expert in solution 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".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.