At 2100 hours on a Monday, one litre of dextrose 5% is set up to run at 50 mL/h. When will the bag be finished?

At 2100 hours on a Monday, one litre of dextrose 5% is set up to run at 50 mL/h. When will the bag be finished?

• A. 0900 h Tuesday
• B. 1700 h Monday
• C. 1500 h Tuesday
• D. 1700 h Tuesday

Answer: (D)

The key idea is how long it takes to deliver a volume at a constant flow rate: time equals volume divided by rate. Here, 1 liter is 1000 mL, and the infusion is running at 50 mL per hour. So the time to finish the bag is 1000 ÷ 50 = 20 hours. Start time is 21:00 on Monday. Adding 20 hours brings you to 17:00 on Tuesday (20 hours after 21:00 crosses midnight after 3 hours, then 17 more hours into Tuesday). Therefore, the bag finishes at 1700 h on Tuesday.

The key idea is how long it takes to deliver a volume at a constant flow rate: time equals volume divided by rate. Here, 1 liter is 1000 mL, and the infusion is running at 50 mL per hour. So the time to finish the bag is 1000 ÷ 50 = 20 hours.

Start time is 21:00 on Monday. Adding 20 hours brings you to 17:00 on Tuesday (20 hours after 21:00 crosses midnight after 3 hours, then 17 more hours into Tuesday). Therefore, the bag finishes at 1700 h on Tuesday.