Of what type of solutions
like any type
I would say that La Nina is responsible for dry conditions in California and typically it is the year after La Nina that the dryness turns often to severe drought. Drought can be bad for agriculture requiring a lot more irrigation and posing a drain on water resources which decrease also during a drought,
Density is the ratio of mass to the volume.
The mathematical expression is given as:

Now, density of isooctane = 
Volume = 
Since, 1 gallon = 3.78 L
So, 3.8 gal = 
= 
As, 1 L = 1000 mL
Therefore,
= 
Volume in mL = 
Put the values,


= 
Hence, mass of 3.8 gal of the gasoline is
.