physics problem?

Question

Lewis set a world record for the 100.0m run with a time of 9.86s. If, after reaching the finish line, Mr. Lewis walked directly back to his starting point in 90.9s, what is the magnitude of his average velocity for the 200.0m?

Answer 1

v = dx/dt

v = (200)/(90.9 + 9.86)

v = 1.98 m/s

Although the answer seems to be 1.98 m/s, it's really 0 m/s. However, the average SPEED is 1.98 m/s. Velocity equals displacement over time. His total displacement was 0 m, because he walked BACK to the starting position.

Answer 2

the answer is surprisingly 0m/sec. because velocity is vector, it has direction. so better read the book carefully.