DS - Topic Average ; GMAT around the corner

[soni_pallavi]

Q1) How many gallons of water should be added to the mixture to make the average value of the mixture $480 per gallon

1)5 gallons of Milk type 1 is mixed with 6 gallons of Milk type 2

2)Milk of type 1 is 600$ per gallon and the cost of type 2 is 90% of cost of Milk 1.

Is the answer C??

Thanks

[eaakbari]

Well answer seems to be E as there is no mention of water in either of the statements.

Whats the source?

[Anindya Madhudor]

Both statement could be used to solve the problem assuming water costs nothing.