Velocity from position data

A toy car's position was measured every half second, with small errors of measurement. Real data never comes as a formula. You will make the program find the velocity on each half second from the slope between readings, then the car's acceleration, and its velocity at $t = 4\ \text{s}$.

The idea. Between two readings, the velocity is about

and it belongs to the middle of that half second.

Your tasks.

1. Inside the loop, work out the velocity between reading k and reading k + 1.
2. Find the average acceleration, from the first velocity to the last.
3. Estimate the velocity at $4\ \text{s}$: the mean of the two velocities whose middles are $3.75\ \text{s}$ and $4.25\ \text{s}$.