When you arrange the data in ascending order, you get:

 6          9          12        19        23        34        43        54        56        69        74        87

If number of observations is odd then median is the  $\left(\frac{n}{2}\right)$th term

If it is even then median is the mean of the  $\left(\frac{n}{2}\right)$th and ($\frac{n}{2})+1)$ th term.

Here the number of observations is 12 - even,

Therefore, the median will be an average of $6^{th}$ and $7^{th}$ observation.

 So, Median=$\frac{34+43}{2}$=$\frac{77}{2}$=38.5.