Answer:
2 m south
Step-by-step explanation:
Displacement is measure of change in the position of an object. It is a vector quantity, that is, it has both magnitude and direction.
When the child walked 4 m south, its displacement is 4 m south.
Then it moved 2 m back opposing direction to the north. The resultant displacement is 4 - 2 = 2 m south.
Then it moved 5 m south, same direction, displacement becomes 2 + 5 = 7 m south.
And finally, it moved 5 m north, opposing direction. 7 - 5 = 2 m south.
The final displacement of the child is 2 m south.