SOLUTION: I am working on mixture problems right now , here is an example of one that I can solve... A chemist has 40 ml. of a solution that is 50% acid. How much water should he add to make

Question 230583: I am working on mixture problems right now , here is an example of one that I can solve... A chemist has 40 ml. of a solution that is 50% acid. How much water should he add to make a solution that is 10% acid? My text book shows the steps to solve the problem.
.50(40) + 0 = .10(40+ x)
2000 = 400+ 10x
1600 = 10x
160= x

I can solve the problem when I have to decrease the percent. What I am having trouble with is when I am asked to INCREASE the percentage. Here is the problem I need help with.
If 800 ml of a juice drink is 15% grape juice, how much grape juice should be added to make a drink that is 20% grape juice? I am not sure where to start. I would appreciate any help that you have to offer.
Thanks,
Horus2
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
If 800 ml of a juice drink is 15% grape juice, how much grape juice should be added to make a drink that is 20% grape juice?
---------------
The other 85% is water = 800*0.85 = 680 ml of water.
Add juice to make that 680 ml of water 80% of the solution.
If 680 ml is 80%, then the total solution is 680/0.8 = 850 ml
--> add 50 ml of juice.

RELATED QUESTIONS
Hi, here is an science and medicine word problem that I think I have worked out and I... (answered by BrittanyM)

A chemist has two solutions of H2s04. One has a 40% concentration and the other has a 25% (answered by Jeef Gorrdon)

When working with percent mixture problems, can the final mixture have a percentage... (answered by ankor@dixie-net.com)

A chemist has 300 millileters (mL) of solution that is 18% acid. How many millileters of (answered by stanbon)

Can someone help me on ths problem? I need to solve the following application:... (answered by stanbon)

A chemist needs 240ml of a 50% Solution but only has 32% and 76% solutions to mix. How... (answered by richwmiller)

I have been working on this problem for 1 hour now and I am having troubles with it. I... (answered by checkley71)

Please check my answer Instructions: I am supposed to solve the following application: (answered by stanbon)

I am trying to work a problem that my teacher gave me on a worksheet. We have worked... (answered by Earlsdon)