Conversion of dosage based on body weight

Question

Infant ibuprofen containes 100mg/5.0mL suspension. The recommended dose is 10mg/kg body to weight. How many mL of this suspension should be given to an infant weighing 18 lb?

That's not a serious question. Don't take that or the answer as advice. I am not responsible for anything bad can happen.

Answer 1

$18$ lb $\approx$ $8.16$ kg

$10$ mg per $1$ kg gives $81.6$ mg per $8.16$ kg.

Per $100$ mg, there is $5$ mL, so per $81.6$ mg there is $\dfrac{81.6}{20}=4.08$ mL of suspension.

Answer 2

The child weighs 8.18kg.

So at 10mg per kg thats 81.8mg for a dose...

The suspension holds 100mg for every 5mL, so give about 4mL

I am not responsible if something bad happens. Note that 4mL (4 millilitres) is not very much at all.