Posted by cleondra on .
you need to prepare 180g of a 10% cream using 30% stock cream and a cream base.how much needed of each

pharmacy technician 
cleondra,
when using 1% cream and a 6% cream to produce a 4% cream how many parts of each initial ingredient will be needed?

pharmacy technician 
DrBob222,
180g of 10%A contains 180*0.1 = 18 g of A. How much of the 30%A must you take to obtain 18g? Won't that be 0.3*?gA = 18g A and ? = 60g.
So you take 60g of the 30% stuff, add 120 g cream base to give 180 g total. What percent is that? Its (18g/180)*100 = 10%