Following is the graph corresponding to the uniformly accelerated motion

a) Velocity at 2.5 seconds is 7 m/s.
b) Acceleration = slope of velocity time graph
= \(\frac{(14-2)}{(6-0)}\)
= 2 m/s2
c) Distance covered in last 4 seconds is the area under the curve for last 4 second
i.e.
Total distance covered in last 4 seconds
= area under ABCD
= area of ABED + area of BCE
= ((6-0)x(6-2)) +\(\frac{(14-6)\times(6-2)}{2}\)
= 24 + 16
= 40 m