Question

how many grams of 2.5% hydrocortisone cream should be mived with 360 g of 0.25 to make a 1% hydrocortisone cream

Answer 1

By proportion, you get
2.5%-1%=1.5
1%-0.25%=0.75
Ratio=1.5:0.75=2:1
To make the mixture, we use the inverse of the ratio, therefore
Mixture=1:2, or
120g of 2.5% and 240g of 0.25% make 360g of 1% (assuming both have same density).
Check: (120*.025+240*.0025)/360=1%

You can also solve this algebraically:
Let x=number of grams of 2.5%, then
360-x=number of grams of 0.25%
We want
0.025x+0.0025*(360-x)=360*0.01
0.0225x=3.6-0.9=2.7
x=2.7/0.0225=120g of 2.5%
(360-x)=240g of 0.25%

Answer 2

So what is the answer ?

Answer 3

180