A physician orders ibuprofen q4-6h for fever for a 90-lb child. The usual adult dose is 400 mg q4-6h. Ibuprofen 100 mg/5 ml is the available medication. What volume of medication should be given to the child per dose?
1) 1.2 ml
2) 3.6 ml
3) 12 ml
4) 16 ml