For the life of me, I can't get the equation (IS)(IV)=(FS)(FV). it's difficult for me for some reason to tell apart the difference between an alligation math question, or a solution question. I know pretty much all I need to know on my test, and the math part is my brick wall that I just cannot get past, can anyone give me tips on better figuring out these equations and telling the difference! Oh, and here's the math question I need help with:
If 200mL of sterile water for injection is added to an 85mL of an 81% stock solution, what is the percentage strength of the resulting solution?
A. 16.42% B. 24.16% C. 34.43% D. 57.16%
Reply by Keith (Phoenix, AZ)
Lets, get something clear for you.
Alligation is only used when you :
1. Know what soluton you are trying to mix. 2. Have a higher strength and a lower strength to work with.
As such, the question above does not fit into those requirements.
Instead of (IS)(IV)=(FS)(FV), I use C1V1=C2V2, it's the same thing, and so whichever you can remember is best for you.
I recorded a video on YouTube about this kind of basic algebra. It's about 12 minutes long and I explain how to work through (IS)(IV)=(FS)(FV) type equations. In the video, you'll see me use C1V1=C2V2, but just keep in mind that it's all the same.