Let 1st talk about boat which is sailing in the sea
it is 3km far and in five minutes he will travel 5/60 *1.5 = 0.125 km
so total distance the boat at shore had to cover in five minutes is 3.125 km
so speed = distance by time = 3.125 /1/12 =37.5 km/hr
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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.:)
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