A dehydrated patient needs a 6.4%saline IV. Unfortunately the hospital only has bags of 6% and 8% saline . How many of each of these solutions should be mixed together to yeild 1 liter of the desired concentration?

Solution:

6% saline: x

8% saline: y

So the equation is

x + y = 1

6%x + 8%y = 6.4%*1

We solve it

x = 0.8

y = 0.2

So

6% saline: 0.8 liter

8% saline: 0.2 liter