You're actually on the right track conceptually, but the error is in unit conversion—the question is asking for mL/hr, but your answer likely gave you time in minutes, and you didn't convert that to hours before calculating the final rate.
Let's walk through it step by step:
Given:
0.5 g vancomycin = 500 mg
Volume = 100 mL
Max rate = 10 mg/min
Step 1: Figure out how long it takes to give 500 mg at 10 mg/min
500 mg ÷ 10 mg/min = 50 minutes
So the entire 100 mL must be infused over 50 minutes.
Step 2: Convert 50 minutes to hours
50 minutes ÷ 60 = 0.833 hours
Step 3: Calculate mL/hr
100 mL ÷ 0.833 hr ≈ 120 mL/hr
Correct answer: 120 mL/hr
Where you went wrong:
You got the infusion time correct (50 minutes), but you likely didn't convert it to hours before using it in the mL/hr formula. Since infusion pumps are set in mL/hr, time has to be in hours, not minutes.