5 times, but...

it's rediculous for a person to swim 3m/s, which means he can finish 100m in 33 seconds. i am a swimmer, so that it really doesnt make sense to me.

3 minutes * 60 seconds = 180 seconds
A = 180seconds * 3meters/second = 540 meters
540 meters / 90 meters = 6 times
B = 180seconds * 2meters/second = 360 meters
360 meters / 90 meters = 4 times
use a rectangle to represent the time, in which draw 3 upside down triangles for A and 2 normal triangles for B.
A and B intersect 5 times.