After constitution of a dry powder, each 5 mL of ampicillin for oral suspension contains 250 mg of ampicillin in package sizes to prepare 100 mL, 150 mL, or 200 mL of suspension. Which package size should be dispensed for a 20-kg child who is to take 50 mg/kg/day total, q. i.d., in equally divided and spaced doses for 10 days?