A nurse is preparing to administer procaine penicillin G 50,000 units/kg IM once daily to a child that weighs 55 lb. The amount available is procaine penicillin G injection 600,000 units/mL. How many mL should the nurse administer? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)

To calculate the dosage of procaine penicillin G for the child, first convert the child's weight from pounds to kilograms, knowing that 1 kilogram equals 2.2 pounds. The child weighs 55 pounds, which is equivalent to 25 kilograms (55 ÷ 2.2). Next, multiply the child's weight in kilograms by the prescribed dosage of 50,000 units/kg, resulting in a total dosage of 1,250,000 units (25 kg × 50,000 units/kg). Finally, divide the total dosage by the concentration of the available medication, 600,000 units/mL, to find the volume to administer. This results in approximately 2.08 mL (1,250,000 units ÷ 600,000 units/mL). Therefore, the nurse should administer 2.1 mL.