a boat travels 30 km upstream in the same amount of time it takes to travel 60 km downstream in the same river.if the speed of the river is 4 km/h, find the speed of the boat in still waier.
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Answer: Speed of the boat in still water = x km/ hr
Speed of the river = 4km/ hr
Speed of the boat upstream = x-4 km/hr
Speed of the boat downstream = x+4 km/ hr
Distance travelled upstream = 30km
Distance travelled downstream = 60km
t1 = times taken to travel upstream
t2 = time taken to travel downstream
Speed = distance / time
Both takes same time to travel upstream and downstream
t1 =t2
s1/v1
time = distance / speed
30 / x-4 = 60 / x+4
x+4 = 2 (x-4)
x+4 = 2x - 8
x= 12
Speed of boat in still water = 12 km/hr
Hope it will be helpfull and follow
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