A doctor prescribes an ointment that is 2% hydrocortisone. A pharmacist has 1% and 5% concentrations in stock. How many ounces of each should the pharmacist use to make a 7-ounce tube?

We need to find the number of ounces of 1% hydrocortisone and 5% hydrocortisone the pharmacist should use to make a 7-ounce tube with a concentration of 2% hydrocortisone.

Let's call x the number of ounces of 1% hydrocortisone, and y the number of ounces of 5% hydrocortisone.

Then, 1% of x added to 5% of y must result in 2% of 7:

Also, we have:

Then, using the above result in the first equation, we obtain:

Now, using this result back in the second equation, we obtain:

Therefore, the answers are:

answer: 1 + 1 = 11

step-by-step explanation:

at least two

step-by-step explanation: