Answer:
25 seconds
Explanation:
Assuming the woman is accelerating at a constant rate of 
from the initial velocity, u=4.20 m/s, to the final velocity, v=5.00 m/s.
Let she takes t seconds to cover the distance, s=115 m.
As acceleration, 
Now, from the equation of motion
[ from equation (i)]
seconds.
Hence, she takes 25 seconds to walk the distance.
Since this is a distance/time graph, the speed at any time is the slope
of the part of the graph that's directly over that time on the x-axis.
At time t1 = 2.0 s
That's in the middle of the first segment of the graph,
that extends from zero to 3 seconds.
Its slope is 7/3 . v1 = 7/3 m/s .
At time t2 = 4.0 s
That's in the middle of the horizontal part of the graph
that runs from 3 to 6 seconds.
Its slope is zero.
v2 = zero .
At time t3 = 13 s.
That's in the middle of the part of the graph that's sloping down,
between 11 and 16 seconds.
Its slope is -3/5 . v3 = -0.6 m/s .
