answer;
18.5 seconds
explanation;
velocity is distance covered per unit time; it is given by displacement divided by time.
thus; time = displacement/velocity
total time = total displacement/velocity
total distance = 5000 meters south
total time = 5000/4.5
= 1111.11 seconds
but; 1 minute = 60 sec
thus; 1111.11 /60
= 18.51 seconds
thus; the time taken is 18.5 seconds