A boy recorded the weight of some of his friends as $32\text{kg}$, $30\text{kg}$, $40\text{kg}$, $65\text{kg}$, $54\text{kg}$, $38\text{kg}$, $36\text{kg}$, $45\text{kg}$, $50\text{kg}$, $52\text{kg}$, $40\text{kg}$. What is the median weight?

First, count the total number of observations ($N$). Here, $N=11$ (an odd number).
Next, arrange the weights in ascending order:

$$30,32,36,38,40,40,45,50,52,54,65$$

For an odd number of items, the median is the value of the $\left(\frac{N+1}{2}\right)$ -th term:

$$\text{Median index}=\frac{11+1}{2}=6\text{-th term}$$

Looking at our ordered list, the 6th term is $40$.
Therefore, the median weight is $40\text{kg}$.