A 12-year-old child weighing 39 kg is ordered metronidazole at a maintenance IV 8-hourly dose for the treatment of gastroenteritis. The recommended maintenance dose of metronidazole is 7.5 mg/kg/dose 8 hourly. What dose can be given safely? Metronidazole comes prepared as an infusion consisting of 500 mg in 100 ml. How many millilitres of this preparation need to be administered?