you need to find the velocity at:

t = 2.0 sec

t=2.5

t=2.1

t=2.005

add v(2) and v(2.1) and divide by 2 to get the average.

I THINK YOU ARE ACTUALLY TRYING TO FIND THE AVERAGE ACCELERATION???????

AVE ACCEL = (v,final – v,initial)/(t,final-t,initial)

1st time interval

a,ave = [ v(2.5) – v(2.0)] / (2.5-2.0)

= [ 0 – 16 ] / (0.5) = -32 ft/s^2

2nd time interval

a,ave = [ v(2.1) – v(2.0)] / (2.5-2.0)

= [ 13.44 -16 ] / (0.1) =

= [-2.56]/0.1 = -25.6 ft/s^2

what you are doing is finding

v(0.5)/(-0.5)

v(0.1)/(-0.1)

you are just finding the velocity at a certain time, and dividing it by that time. you are not finding the change in velocity over that time, starting at t=2.0.

v(0.5) just happens to be 16 … you get a right answer, even though your physics/math is not correct.

an unfortunate problem set-up.

good luck