How many grams of 2.5% hydrocortisone cream should be mixed with 360 g of 0.25% cream to make a 1% hydrocortisone cream?
Let's denote the amount of 2.5% hydrocortisone cream to be mixed as x grams.
The amount of hydrocortisone in the 2.5% cream is (2.5/100) * x = 0.025x grams.
The amount of hydrocortisone in the 0.25% cream is (0.25/100) * 360 = 0.9 grams.
To make a 1% hydrocortisone cream, the total amount of hydrocortisone should be 1% of the total weight of the creams.
Thus, 0.025x + 0.9 = (1/100) * (360 + x).
0.025x + 0.9 = 3.6 + 0.01x.
Moving all terms involving x to one side of the equation, we have:
0.025x - 0.01x = 3.6 - 0.9,
0.015x = 2.7,
x = 2.7 / 0.015,
x ≈ 180.
Therefore, approximately 180 grams of the 2.5% hydrocortisone cream should be mixed with 360 g of the 0.25% cream to make a 1% hydrocortisone cream.