SOLUTION: A pharmacist is to prepare 15 milliliters of special eye drops for a glaucoma patient. The eye-drop solution must have a 5% active ingredient, but the pharmacist only has 20% solut

Question 768567: A pharmacist is to prepare 15 milliliters of special eye drops for a glaucoma patient. The eye-drop solution must have a 5% active ingredient, but the pharmacist only has 20% solution and 2% solution in stock. How much of each type of solution should be used to fill the prescription?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = ml of 20% solution needed
Let = ml of 2% solution needed
--------------
{1}
(2)
----------------------------
(2)
(2)
(2)
--------------------
Multiply both sides of (1) by
and subtract (1) from (2)
(2)
(1)

and, since
{1}
(1)
(1)
2.5 ml of 20% solution are needed
12.5 ml of 2% solution are needed
--------------
check:
(2)
(2)
(2)
(2)
(2)
OK
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