To calculate the flow rate for the blood administration set, we need to divide the total volume of red blood cells (450 mL) by the time it will take to administer (4 hours).

Flow rate = Volume / Time

Flow rate = 450 mL / 4 hours

Flow rate = 112.5 mL/hour

Now, we need to convert the flow rate from mL/hour to drops/minute using the drop factor of 17.

Flow rate (drops/minute) = Flow rate (mL/hour) / Drop factor

Flow rate (drops/minute) = 112.5 mL/hour / 17

Flow rate (drops/minute) ≈ 6.62 drops/minute

Therefore, the flow rate for the blood administration set is approximately 6.62 drops/minute.