Question

The dosage of a certain medication is determined by a patient's body weight. This medication's dosage is 2.5 mg per kilogram of body weight. What would be the dose for a patient who weighs 72 pounds? (1 lb = 0.453 kg) (Doses are rounded to the nearest 25 mg.)

Show work please

Answer 1

75 mg

Explanation:

You want the dose for a 72 pound person at the rate of 2.5 mg/kg.

Unit conversion

We multiply by conversion factors that cancel unwanted units, leaving the units we want.

At the end of the unit conversion, we need to determine if the calculated dose is closer to 75 mg or 100 mg. It is less than 87.5 mg, so is closer to 75 mg.

`\frac{2.5\text{ mg}}{\text{kg}}*(72\text{ lb})*\frac{0.453\text{ kg}}{\text{lb}}=2.5*72*0.453\text{ mg}\approx81.54\text{ mg}\\\\\approx\boxed{75\text{ mg}}`

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Additional comment

We found the nearest 25 mg dose by dividing by 25 mg, and rounding the 3.26 dose result to 3 doses of 25 mg each.