a boat running down stream covers a distance of 16km in two hours .while covering a same distance upstream it takes 4hours .what is the speed of the boat in still water?"
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distance=16 km
time= 2hr
down stream speed= 16/2= 8km/hr
upstream speed=16/4= 4km/hr
boat's speed=x km/hr
river speed= y km/hr
x+y=8
x=8-y ....(1)
x-y=4
x=y+4.....(2)
8-y=y+4
8=2y+4
2y=4
y=4/2=2 km/hr
x+y=8 ...so x+2=8
x=6
speed of the boat= 6km/hr
time= 2hr
down stream speed= 16/2= 8km/hr
upstream speed=16/4= 4km/hr
boat's speed=x km/hr
river speed= y km/hr
x+y=8
x=8-y ....(1)
x-y=4
x=y+4.....(2)
8-y=y+4
8=2y+4
2y=4
y=4/2=2 km/hr
x+y=8 ...so x+2=8
x=6
speed of the boat= 6km/hr
jayantu:
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