Question

Justin is taking an anti-inflammatory drug and the instructions say that the patient must receive 11 mg for each 20 kg of body weight. If Justin weighs 253 lb, what dosage should he receive?

Answer 1

First, we need to convert 253 lb to kilograms. Given that 1 kg is equivalent to 2.205 lb, then:

$253\text{ lb = }253\text{ lb}\cdot\frac{1\text{ kg}}{2.205\text{ lb}}\approx114.74\operatorname{kg}$

The dosage Justin should receive is directly proportional to his weight. Given that a dosage of 11 mg corresponds to a weight of 20 kg, then to find the dosage that corresponds to 114.74 kg we can use the next proportion:

$\frac{11\text{ mg}}{x\text{ mg}}=\frac{20\operatorname{kg}}{114.74\operatorname{kg}}$

Solving for x:

$\begin{gathered} 11\cdot114.74=20\cdot x \\ \frac{1262.14}{20}=x \\ 63.1\approx x \end{gathered}$

He should receive a dosage of 63.1 mg