Answer:
0.4 mL
Step-by-step explanation:
I was able to do this in my head, but...
If you just take the fraction of 2000 units/5000 units/mL, then the units will cancel out and you're essentially left with 2000/5000 mL. 2000/5000 can be reduced to 2/5, and as a decimal, 2/5 comes out to 0.4 or 40%.
So, 0.4 mL (about half) would be administered to the patient.