Question

A pharmacist must mix 12 fl oz of cough syrup that contains 25% active ingredient with flavored syrup that contains no active ingredient. How many fluid oz of flavored syrup must the pharmacist add to create a mixture containing 10% active ingredient?

Answer 1

Find the amount of active ingredient:
12 * 25% = 3 oz. active ingredient.
Now you want to make 10% active ingredient with those 3 oz.
3/x = 10/100
x = 30 oz. //total volume
So you need to add 18 oz to get 30 oz total.

Answer 2

Thank you.