Nope.

Average speed = change in distance / change in time

Anything can happen in between any specified initial velocity and final velocity, so the average speed doesn't really help.

Consider the following data series (numbers representing velocity each second):

5 4 3 3 5 100

• Average velocity: 20
• Initial velocity: 5

Furthermore, the fact that speed -- scalar -- truncates information about direction that velocity requires just makes this even more hopeless.

But we can if we assume acceleration is constant (which is often the case in physics, but it should say so in the question explicitly) it may be possible.