To make a 1-ounce tube of the ointment that is 4% hydrocortisone, the pharmacist needs to use 0.04 ounces of the active ingredient (hydrocortisone).
The pharmacist has 1% and 5% concentrations in stock, therefore he needs to use 0.96 ounce of the 1% concentration and 0.04 ounces of the 5% concentration.
The pharmacist should use 0.96 ounces of the 1% concentration and 0.04 ounces of the 5% concentration to make a 1-ounce tube of the ointment with the correct percentage of hydrocortisone.
It's important to note that it's important that the pharmacist needs to mix the correct amount of hydrocortisone to get the desired percentage, and also that the pharmacist needs to check the final percentage of the ointment before dispensing to ensure the safety and efficacy of the medication.