A boat travels upstream at the speed of 20 km/h and downstream at the speed of 30 km/h. What is the speed of the boat in still water?
Answer & explanation
Correct answer: option 3
Let speed of boat = B km/h
& Speed of Stream = S km/h
Speed of Downstream = ( B + S ) km/h
Speed of Upstream = ( B - S ) km/h
According to question ,
B + S = 30 km/h -------(1)
B - S = 20 km/h --------(2)
Adding equation 1 & 2
2B = 50 km/h
B = 25 km/h
So , Speed of Boat = 25 km/h