Aboat sails along the shore. to an observer, the boat appears to move at a speed of 22 m/s, and a man on the boat walking forward appears to have a speed of 23.1 m/s. how long does it take the man to move 3 m relative to the boat?

2.7 s

Explanation:

The boat moves (relative to the observer) at 22 m/s, while the man moves at 23.1 m/s (still relative to the observer), therefore the speed of the man (relative to the boat) is

The time the man takes to walk 3 m (relative to the boat) is equal to the ratio between the distance (3 m) and his speed, relative to the boat: