A speed boat at he shore wants to overtake a sail boat that is 3 km out at sea. If the sail boat is travelling away from the shore at 1.5 km/hr, how fast should the speed boat travel to overtake the sail boat in 5 minutes from the shore

Answer 1

After 5 minutes the sailboat will be
3 + 1.5((5/60) km or 3.125 km from shore

so the speed boat has to go 3.125 km in 5 minutes to catch it:
speed = distance/time
= 3.125/(5/60)
= 37.5 km/h

Answer 2

37.5KM/hr