In Michael Johnson’s world-record 400 m sprint, he ran the first 100 m in 11.20 s; then he reached the 200 m mark after a total time of 21.32 s had elapsed, reached the 300 m mark after 31.76 s, and finished in 43.18 s.

a. During what 100 m segment was his speed the highest?

b. During this segment, what was his speed in m/s?