SOLUTION: In a certain medical test designed to measure carbohydrate tolerance, an adult drinks 3 ounces of a 80% glucose solution. When the test is administered to a child, the glucose conc

Question 499220: In a certain medical test designed to measure carbohydrate tolerance, an adult drinks 3 ounces of a 80% glucose solution. When the test is administered to a child, the glucose concentration must be decreased to 50%. How much 80% glucose solution and how much water should be used to prepare 3 ounces of 50% glucose solution?

Answer by oberobic(2304) (Show Source):
You can put this solution on YOUR website!
In solving mixture problems, you have to determine how much "pure" stuff you need.
.
For adults and children, you need 3 oz of fluid.
.
The child's the solution must be 50% glucose.
So, the child's 3 oz will need to have 1.5 oz of "pure" glucose and 1.5 oz of other stuff (likely water, but it doesn't matter).
.
You have on hand 80% solution.
So for each oz you have .8 oz of glucose.
To get 1.5 oz of pure glucose, you need:
.8x = 1.5
8x = 15
x = 15/8
x = 1 7/8 oz of the 80% solution
.
You need 3 oz in total, so add 1 1/8 oz of water to 1 7/8 oz of of the 80% glucose solution to produce 3 oz of 50% solution.
.
Done.