# The doctor orders a medication as #"5.00 mg/kg"# of body weight. The dosage the nurse gives the patient is #"425 mg"#. How much does the patient weigh in pounds?

##### 3 Answers

#### Explanation:

You have a little mor econverting to do to solve this one.

You know that the drug dosage is set to *pounds*.

To start, you can convert the dosage from miligrams per kilogram to *miligrams per pound* by using the conversion factor

#"1 kg" ~= "2.2046 lbs"#

This means that you have

#5.00"mg"/color(red)(cancel(color(black)("kg"))) * (1color(red)(cancel(color(black)("kg"))))/"2.2046 lbs" = "2.268 mg/lbs"#

So, your patient needs **2.268 mg** of the drug *per pound of body weight*. This means that if you supply **425 mg**, his body weight must be

#425color(red)(cancel(color(black)("mg"))) * "1 lbs"/(2.268color(red)(cancel(color(black)("mg")))) = "187.39 lbs"#

Rounded to three sig figs, the number of sig figs you gave for the dosage and mass of drug administered, the answer will be

#color(green)("187 lbs")#

The patient weighs

#### Explanation:

**Given/Known**

Medication mass/body mass:

Dosage:

Just over 187 lb

#### Explanation:

Therefore

But you want the weight of the patient in lb, so you need to build in the conversion

Therefore the final equation is:

Plug in the numbers and you get 187.43 lb.