Answer:
The speed of the boat in still water is 33 km/h
Step-by-step explanation:
Let us denote the speed of the boat in still water as x km/h.
Thus;
Since the speed of the stream is 3 km/h, then while going downstream, the total speed on the boat would be; (x + 3) km/h
Formula for distance = speed x time
Since we are told that the time taken to cover the distance downstream is 5 hours, then;
Distance covered in 5 hours = 5(x + 3) km
Therefore, distance between A and B is 5(x + 3) km
However, while going upstream the boat will work against the water current.
Therefore, its speed upstream will be (x − 3) km/h.
we are told that the time taken to cover the distance downstream is 6 hours, then;
Distance covered in 6 hours = 6(x − 3) km
Therefore, distance between A and B is 6(x - 3) km
The true distance between A and B has to be the same.
So,
5(x + 3) = 6(x - 3)
This gives;
5x + 15 = 6x - 18
15 + 18 = 6x - 5x
x = 33
Therefore, the speed of the boat in still water is 33 km/h
