Speed = (distance) / (time to cover the distance)
Speed = (400 m) / (5.2 minutes)
Speed = (400 m) / (312 seconds)
Speed = 1.28 m/s
There's not enough given information to find his velocity.
(I'll be honest with ya, Flash: 1.28 m/s is no big deal. It's only about 2.87 miles per hour. My dog can walk faster than that, and so can most healthy people. If that's the best you can do, then you probably shouldn't be running around chasing bad guys.)