<image>A shopping mall sold 16 pairs of Li-Ning brand sports shoes in one day. The sales volume of shoes in various sizes is shown in the table below:
.
For the set of data composed of the sizes of these 16 pairs of shoes:
① What are the mode and the median?
② Through calculation: If the mall restocks every 10 days, how should it restock Li-Ning brand sports shoes in the sizes above and explain the reason.