4) Looking at the W/V formula, we know we need to reduce the fraction by half in this case in order to make our denominator go from 200ml - 100ml:
1.50g ÷ 2 ----- 200ml ÷ 2
5) Now, our converted fraction is:
.75g ----- 100mL
6) Now look at the numerator ! Our answer is 0.75% W/V. Now that you have the (bottom) denominator at 100ml, whatever is in the (top) numerator is your % W/V.
Remember: -Don't let the decimals fool you. If you saw a 1 in the numerator, it would be 1%, right ?
-As you get better at this, you'll see that it's all about getting your fraction setup properly and then getting your denominator to 100ml.
That's really the basic rundown on Concentration Percentage as it's used in Pharmacy Tech Math. Whatever program you are studying will likely have a much more detailed approach and several practice problems.
The next step in learning about compounding math is learning about using
, which are used when mixing a preparation of a certain percentage when you have two different strengths to work with. Whatever you do, don't confuse the formulas we have done here with Alligations. You will know distinctly to use an Alligation when the question says you have two different strengths to work with.