In a certain medical test designed to measure carbohydrate tolerance, an adult drinks 6 ounces of a 40% glucose solution. When the test is administered to a child, the glucose concentration must be decreased to 30%. How much 40% glucose solution and how much water should be used to prepare 6 ounces of 30% glucose solution?

4.5 ounces of 40% glucose solution and 1.5 ounces of water.

Explanation:

The new solution will be prepared by adding more solvent, so the relation between concentration and volume is given by:

C1xV1 = C2xV2

Where C is the concentration, V is the volume, 1 represents the initial solution and 2 the final solution.

We want 6 ounces of a solution which 0.3 glucose, so:

0.4xV1 = 0.3x6

0.4xV1 = 1.8

V1 = 4.5 ounces

So, it's necessary 4.5 ounces of the 40% glucose solution. The volume of water (Vw) will be the total volume less the volume of the solution:

Vw = 6 - 4.5

Vw = 1.5 ounces