# Thread: Need help with Percentage Word Problems.

1. ## Need help with Percentage Word Problems.

There are two word problems that are giving me alot of trouble for an assignment that I have to do.

A 50% saline solution mixed together with a 30% saline solution to get 30L of a 46% concentrated saline solution. How many litres of each are needed to be mixed?

You invest a total of $1800 into two diffrent investments. One investment returned 9% and the other returned 6%. If the interest on the 9% was$102 more of a return than the return of the 6% investment then how much of your $1800 was in each seperate account? I don't know how to set up any of these problems. If I could have help with the set up I could do it. These are the only problems on the sheet giving me problems. Thanks for your assistance. 2. Originally Posted by (?)G You invest a total of$1800 into two diffrent investments. One investment returned 9% and the other returned 6%. If the interest on the 9% was $102 more of a return than the return of the 6% investment then how much of your$1800 was in each seperate account?
Let A be the amount of the first investment

Let B be the amount of the second investment

Originally Posted by (?)G

You invest a total of $1800 into two diffrent investments.$\displaystyle A+B = 1800$Originally Posted by (?)G If the interest on the 9% was$102 more of a return than the return of the 6% investment then how much of your $1800 was in each seperate account?$\displaystyle 1.09A = 102 +1.06B$Can you solve this system?$\displaystyle A+B = 1800\displaystyle 1.09A = 102 +1.06B$3. Thanks, I knew the A+B=$1800 part, but the other part really threw me, with the one returned 9 percent was $102 more of a return than the 6 percent investment. So You have the 1.09, The 1 represents 100 percent, plus an extra 9 percent on top of one and 6 percent on top of the other? What about the saline solution one, I can't even make heads or tails of even the first equation. Here is my work just in case it can help somebody else out: A= -B+ 1800 1.09( -B + 1800) =$102 + 1.06B "Equal Quantities Method"

1860 = 2.15B

1860/2.15 = 2.15B/2.15B

(($865.12 = B)) 1.09A = 102 + 1.06 (865.12) 1.09A = 102 + 917.03 1.09A/1.09A = 1019.03/1.09 (($934.89= A))

When you add A and B up it is $1800.01, With rounding off certain numbers it is .01 over the$1800, but it's around the same area.

4. Originally Posted by (?)G

A 50% saline solution mixed together with a 30% saline solution to get 30L of a 46% concentrated saline solution. How many litres of each are needed to be mixed?
I'm thinking to tackle this one similar to that of the second question

A and B are the volumes of the 2 mixtures.

$\displaystyle 50\%\times A + 30\%\times B = 46\%\times (A+B)$

$\displaystyle A+B= 30$

can you finish it?

5. Originally Posted by pickslides
I'm thinking to tackle this one similar to that of the second question

A and B are the volumes of the 2 mixtures.

$\displaystyle 50\%\times A + 30\%\times B = 46\%\times (A+B)$

$\displaystyle A+B= 30$

can you finish it?
Was I right for the last one, by the way?

6. Looks good.