Answer: 4m
Explanation:
Since the angle of incidence of a plane mirror can be anything from 0 to 90°
Assuming that the place is a perfectly square 4×4m room
The incident ray would be 45° for the choir(object) at a 4m distance, this is still within the range of values.
We do not forget also, that the focal length of a plane mirror is infinity, the organist would in fact see farther than 4m if need be. And wider
Displacement depends upon the path taken as it is a vector.
From your problem above we would have a total displacement of;
Defining +x direction as east and -x direction as west
6east-3west+1east+6east-7west
6-3+1+6-7=3 blocks east or + x-direction
So even though they walked a total of 17 blocks it ends up only being 3 blocks total in +xdirection that was travelled by displacement.
Any questions please ask.
Dart board 3 represents high accuracy but low precision