Medications are often prescribed in dosages of milligrams of medication/kilogram of the body mass (weight).

Question

A doctor writes a prescription for a medication at 5mg/kg.

A.) How many milligrams will a person who weighs 60 kg need to take?

B.) If the medication is dispensed as a liquid containing 100 mg of the medication per I mL of the liquid, how many millileters of the liquid will the person need to take?

Answer 1

A. You just multiply the dose per kg times the number of kg to get the total dosage.  So 5 * 60 = 300 mg

 

B. In this case you can kind of tell just by looking.  If they need 300 mg and each ml has 100 mg, then you can see that they will need 3 ml.  In general, though, you would divide the total dosage by the amount per ml to get the number of ml's needed.  So 300 / 100 = 3, so the person will need 3 ml.