Apatient requires an iv of 0.9% saline solution, also known as normal saline solution. how much distilled water, to the nearest milliliter, must be added to 100 milliliters of a 2% saline solution to produce normal saline?

Let the amount of proper amount of water to be added be x milliliters.

the solution of 100 milliliters is 2% saline, means that 2%*100=2 milliliters of the original solution is saline.

after we add x milliliters,  the total volume of the liquid becomes 100+x (milliliters), and 2 milliliters is now 0.9% of the solution, that is:

2 = 0.9% (100+x)
2=0.9+0.009x
0.009x=2-0.9
0.009x=1.1
x=1.1/0.009=122.2 (milliliters)

122.2 milliliters