A boat can travel 8.5 km downstream in 15 minutes and 3.6 km upstream in 8 minutes. what is the speed of the boat in still water ? (in kmph)
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let speed of boat in still water be x
and speed of stream be y.
now time taken in downstream=15=8.5/x+y
or, 15x+15y=8.5.............1
time taken in upstream= 8=3.6/x-y
or, 8x-8y=3.6.................2
dividing 1 by 15 and 2 by 8 and adding both we get,
x+y=8.5/15=0.5666. and x-y=3.6/8=0.45
adding, 2x=1.0166
so, x=0.583 km /minutes
so, x=60×0.5083 km/hr
so, speed of boat in still water is 30.498km/hr.
Thanks.
and speed of stream be y.
now time taken in downstream=15=8.5/x+y
or, 15x+15y=8.5.............1
time taken in upstream= 8=3.6/x-y
or, 8x-8y=3.6.................2
dividing 1 by 15 and 2 by 8 and adding both we get,
x+y=8.5/15=0.5666. and x-y=3.6/8=0.45
adding, 2x=1.0166
so, x=0.583 km /minutes
so, x=60×0.5083 km/hr
so, speed of boat in still water is 30.498km/hr.
Thanks.
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