Overall material and component balances are important concepts to be able to answer the question above. Let x be the amount of water in gallons that should be added to his available mixture. From both balances, the equation below is obtained.
(1)(0.90) + (x)(1) = (1 + x)(0.965)
The equation above shows the balance for water. Solving for x gives an answer of x = 1.857.
Therefore, Hal should add approximately 1.857 gallons of pure water.
