To find the average amount of root beer produced per minute, we divide the total amount of root beer produced by the time taken in minutes.
The factory produced 93 liters of root beer in 4 minutes.
So, we calculate:
\[ \text{Average production per minute} = \frac{93 \text{ liters}}{4 \text{ minutes}} = 23.25 \text{ liters/minute} \]
Therefore, the factory produced an average of 23.25 liters of root beer each minute.