If you wanted to mix pure methane with water and end up with 100 gallons of 90% methane, how many gallons of each should you use?

Question

If you wanted to mix pure methane with water and end up with 100 gallons of 90% methane, how many gallons of each should you use?

Answer 1

Mixture problems look at the amount of each component and also at the amount of the substance you are looking for. 

Here, let x = amount of water, y = amount of pure methane.

x+y = 100 gallons

Now to look at the amount of methane.  Water has no methane in it, so all the methane comes from the pure methane.  

y = .9 (100)

y = 90 gallons

x+ y = 100

x + 90 = 100

x= 10