I heard median of any number of data. Suppose we have a data
[13,23,23,23,54]
The median of this data is is 23.
How we calculate the weighted median of same data (as mentioned above).
** http://en.wikipedia.org/wiki/Weighted_median (this is i get when i Google it. But things are not clear).
If you have your five data the median is just the value appearing in the third position. Now, assume you have $$\begin{array}{cc}\text{data} & \text{weight} \\ 13 & 10 \\ 23 & 3 \\ 54 & 4\end{array}$$ where the weight is the number of times that a given data appears. Now, you have $17$ data. The weighted median is the value in $9$th position, that is, $13.$
In fact, when you compute the median with your data you are actually working with a weighted data
$$\begin{array}{cc}\text{data} & \text{weight} \\ 13 & 1 \\ 23 & 3 \\ 54 & 1\end{array}$$