Good question.
I believe on civil engines, the core exit velocity (the hot bit) is normally just below the speed of sound. At a temperature of, say, 700K (about 400 deg.C) the speed of sound would be about 517 m/s (just over 1000 kts) I am a bit rusty with the figures, and this sounds a little high, but I would say at least about 800 kts. The speed out of the bypass duct would be considerably lower than this.
Re-heated military engines can have higher exit velocities, because they use convergent-divergent nozzles to accelerate the flow to supersonic speeds, but this is very wasteful of fuel.
Please, anybody, correct me if my theory is a little rusty.
Hope this helps.
Pie