Answer
Find out the length of segment GE .
To prove
As shown in the diagram given in the question
G is the centroid of the ΔABC .
By using the properties of the centroid.
The centroid divides each median in a ratio of 2:1.
Thus

As given
BG =24mm
Put in the above

= 12 mm
Therefore the length of segment GE is 12 mm .