Question 1011766:  1.The boys mixed 10 gallons of the 20% pure lemon juice mix and 10 gallons of the 70% pure lemon juice mix, because they wanted 20 gallons of lemonade at a 40% lemon juice mixture. They thought that because 40% was almost halfway between 20% and 70%, they should just mix equal parts of both, but the lemonade turned out too tart. How much of each should they have used to get a final mixture of 20 gallons at 40% lemon juice?  Write your answer in complete sentences. Show all work. 
 Answer by stanbon(75887)      (Show Source): 
You can  put this solution on YOUR website! The boys mixed 10 gallons of the 20% pure lemon juice mix and 10 gallons of the 70% pure lemon juice mix, because they wanted 20 gallons of lemonade at a 40% lemon juice mixture. They thought that because 40% was almost halfway between 20% and 70%, they should just mix equal parts of both, but the lemonade turned out too tart. How much of each should they have used to get a final mixture of 20 gallons at 40% lemon juice? Write your answer in complete sentences. Show all work.  
----- 
Quantity Equation: t + s = 20 gallons 
Lemon content Eq: 20t+70s = 40*20 gallons 
--------------------------------------------- 
Modify for elimination: 
2t + 2s = 2*20 
2t + 7s = 4*20 
------- 
Subtract and solve for "s": 
5s = 2*20 
s = 8 gallons (amt. of 70% mix needed) 
t = 20-8 = 12 gallons (amt of 20% mix needed) 
----------- 
Cheers, 
Stan H. 
------------- 
  | 
 
  
 
 |   
 
 |