$$s = u*t + \frac{1}{2}*a*t^2$$
Here, $$s$$ is the displacement of the object.
Remember that $$\text{Speed} = \frac{\text{Distance Covered}}{\text{Time Taken}}$$ works only for average speed. If the object is accelerating, then, we cannot use the value of the initial speed and the time taken to calculate the distance covered!
We just calculated Jerry's acceleration to be 1.25 m/s2. Using the 2nd EOM, what is the value for Jerry's displacement, $$s$$? (Recall that Jerry's velocity changed from 2.5 m/s at 2 s to 5 m/s at 4 s.)
• $$s = 5*2 + \frac{1}{2}*1.25*2^2$$
• $$s = 2.5*2 + \frac{1}{2}*1.25*2^2$$
• $$s = 2.5*2 + \frac{1}{2}*5*2^2$$
• $$s = 2.5*5 + \frac{1}{2}*1.25*2.5^2$$