Why Does qEt/m Represent Drift Speed in a Conductor?

[anonymousphys]

Homework Statement

v=qEt/m
t=time between each collision
q=charge on particle
m=mass of particle
E=electric field

Why is this the average velocity/drift speed in a conductor?

Homework Equations

The Attempt at a Solution

Doesn't qEt/m = the final velocity of the particle. So isn't the average velocity qEt/(2m)?
Is there something missing in my logic?

Thanks for any help.

 

[anonymousphys]

Still not too sure about this problem. Any help would be much appreciated.

 

[anonymousphys]

In in introductory physics, do we just assume qEt/(2m) = qEt/(m) because the values are so small?