The shoe sizes of five students are: 10, 9, 11 and 4. Find the median shoe size, modal shoe size, and calculate the mean shoe size.

The shoe sizes are $10, 9, 11, 9$.

Number of shoe sizes $n=4$ (even).
Median is the average of the $\frac{n}{2}$th = 2nd and $(\frac{n}{2}+1)$th = 3rd values.

2nd value = 9
3rd value = 10

9.5

Sum = 39

$n = 4$

9.75