SOLUTION: Question A researcher wants a 72 ounce saline solution with a concentration of 7%. She has concentrations of 2% and 14%. How much of each solution must she use to get the desire

Question 1090192: Question
A researcher wants a 72 ounce saline solution with a concentration of 7%. She has concentrations of 2% and 14%. How much of each solution must she use to get the desired concentration?
Answer by ikleyn(52786) (Show Source): You can put this solution on YOUR website!
.

The equation is

0.02*x + 0.14*(72-x) = 0.07*72.   (x = the volume of the 2% solution, in mL).



You need to understand why it is so, but is is SO EASY . . . !

    Both sides of the equation represent the balance of the salt mass in the solutions.



To solve the equation,  multiply its both sides by 100 to get it in more easy form. You will get

2x + 14(72 -x) = 504.


Now simplify and solve for x.


I leave it to you to complete the solution.

There is entire bunch of introductory 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".

RELATED QUESTIONS
A scientist wants a 90-ounce acid solution with a concentration of 12%. She has... (answered by josgarithmetic)

A chemist wants to make 200ml of an acid solution with a concentration of 48%. He wants... (answered by josgarithmetic)

Wilson has a bottle containing 35 millimeters of 15% saline solution and a bottle of 40%... (answered by Finavon)

Joyce has 42 liters of 40% saline solution in a container and plans to add a certain... (answered by lwsshak3)

7 qt of a saline solution was mixed with 4 qt of pure water to make 35% saline solution.... (answered by josgarithmetic,josmiceli)

8 gal. of a saline solution was mixed with 2 gal. of pure water to make a 16% saline... (answered by josgarithmetic,josmiceli)

a chemist wants to mix a 60% saline solution with 20 liters of a 45% saline solution to... (answered by Earlsdon)

lindsay wants to me a 20% saline solution with a 12% saline solution to make 60 ounces of (answered by josgarithmetic)

A chemist has four solutions of a very rare and expensive chemical that at 15% acid (cost (answered by Alan3354)