# Question #07a44

##### 1 Answer

Here's what I got.

#### Explanation:

The problem tells you that the correct dosage is

#"15 mg drug " -> " 1 kg"#

and that the patient has a mass of **total mass** of drug that must be administered to the patient.

To do that, use the correct dosage as a **conversion factor** to take you from the mass of the patient to the mass of the drug

#20 color(red)(cancel(color(black)("kg"))) * overbrace("15 mg drug"/(1color(red)(cancel(color(black)("kg")))))^(color(blue)("given by the problem")) = "300 mg drug"#

Now, assuming that your solution contains **for every** **conversion factor** to take you from the mass of drug to the volume of the solution

#300 color(red)(cancel(color(black)("mg drug"))) * ("5 cm"^2color(white)(.)"solution")/(200color(red)(cancel(color(black)("mg drug")))) = color(darkgreen)(ul(color(black)("7.5 cm"^2color(white)(.)"solution")))#

I'll leave the answer rounded to two **sig figs**, but keep in mind that you only have one significant figure for your data.

**SIDE NOTE** *If you only have* *of drug dissolved in* *of solution, then you can't really administer the* *of drug needed by the patient because you are* *of drug short*.

*This is why I assumed that the solution contains*

*of drug*

**for every***of solution*.