One-half liter of solution for intravenous infusion contains 2 g of drug. how many milliliters of the solution would contain 0.5 mg of drug?

1.25mL of the solution would contain 0.5mg of drug.

Step-by-step explanation:

This is a problem involving conversion of units, that can be solved by rules of three.

In a rule of three problem, the first step is identifying the measures and how they are related, if their relationship is direct of inverse.

When the relationship between the measures is direct, as the value of one measure increases, the value of the other measure is going to increase too.

When the relationship between the measures is inverse, as the value of one measure increases, the value of the other measure will decrease.

Conversion of units is an example of a rule of three in which the relationship between the measures is direct.

First step: How many liters of the solution would contain 0.5 mg of drug?

The problem states that 0.5L has 2g = 2000mg of drug. So

0.5L - 2000mg

xL - 0.5mg

2000x = 0.5*0.5

x = 0.00125L

0.00125L of the solution would contain 0.5mg of drug.

Final step: Conversion of 0.00125L to mL

Each L has 1000 mL. So

1L - 1000mL

0.00125L - xmL

x = 1000*0.00125

x = 1.25mL

1.25mL of the solution would contain 0.5mg of drug.

a is the right answer

yes the total will be same because in both of them the expression.is rearranged but their sign remains the same hence it hss just been shuffled