The median age at which babies master sitting unsupported is months.

Answer;
The median age at which babies master sitting unsupported is six months. 

Explanation;
During four to six months; the babies are really learning to reach out and manipulate the world around them. They are mastering the use of their hands and discovering their voices;
The baby is able to; laugh; reach out for and grab objects, and manipulate toys and other objects with her hands, sit up with support and have great head control.