Final answer:
To determine the start time of the blood infusion, calculate the duration by dividing the total volume by the infusion rate and then subtract this from the end time. The infusion started around 6:54 am when you subtract the infusion duration of approximately 191.4 minutes from the end time of 10:05 am.
Step-by-step explanation:
The student's question asks us to determine the start time of a blood infusion based on the amount infused, the rate of infusion, and the time of completion. To find out when the infusion started, we use the formula: start time = end time - (total volume / infusion rate). Given that 415 ml of blood cells were infused at a rate of 130 ml/hour and the infusion ended at 10:05 am, we first calculate the infusion duration:
Duration = Total Volume / Infusion Rate = 415 ml / 130 ml/hour ≈ 3.19 hours
Since the duration is approximately 3.19 hours, we convert this to minutes for more precision: 3.19 hours × 60 minutes/hour = 191.4 minutes. We then subtract the duration in minutes from the end time of 10:05 am:
End Time (in minutes) = 10 × 60 + 5 = 605 minutes
Start Time (in minutes) = End Time (in minutes) - Duration (in minutes) = 605 minutes - 191.4 minutes ≈ 413.6 minutes
Now we convert the start time back to standard time format:
Start Time (hours) = 413.6 minutes / 60 minutes/hour ≈ 6.893 hours
Start Time = 6 hours + (0.893 hours × 60 minutes/hour) ≈ 6:54 am
So the infusion started at approximately 6:54 am.