You will win a race against a canoe with one paddler....
Or scoot along at a decent enough speed to get to the next fishing hole.
You won't go water skiing or para-sailing...at least not very well. Had a 50 on my old 14' fiberglass...you could almost ski if you were good...but it wasn't easy.
it all depend on how much weight you have in the boat, how it is distributed, if the boat and motor are set up properly. thus really impossible to answer, logically.
Yup -- the answer to that question is akin to asking "how high is up!" Give us a specific year, make, and model of boat and what you consider an average load and perhaps someone with that exact combination can answer your question. Otherwise all we can do is guess.