In 5 mins the sail boat will travel a distance of :
Now its (0.125+3.000)km far from the sea shore.
To cover this distance in 5 mins the speed boat has to travel at a speed of :
Speed = distance/time.
∴speed = (3.125)÷5/60.
∴the speed of the speed boat has to be 37.5km/hr.
hope it helps and pls mark this as best answer.:)