A man can row three quarter of a km. against the river in 11 ¼ minutes and return in 7 ½ minutes. what is the speed of the man in still water?
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Distance=3/4km
time taken upstream=11 1/4 min= 45/4min
time taken upstream (in hours)=45/48*1/60=3/16 hrs
speed upstream = distance (km)/time (in hours)
=3/4 * 16/3= 4kmph
time taken downstream = 7 1/2 = 15/2 min
time taken downstream (in hrs) = 15/2*1/60=1/8 hrs
speed downstream = distance/time = 3/4*8 = 6 kmph
now, speed in still water = 1/2* (4+6)
= 10/2
= 5 kmph
time taken upstream=11 1/4 min= 45/4min
time taken upstream (in hours)=45/48*1/60=3/16 hrs
speed upstream = distance (km)/time (in hours)
=3/4 * 16/3= 4kmph
time taken downstream = 7 1/2 = 15/2 min
time taken downstream (in hrs) = 15/2*1/60=1/8 hrs
speed downstream = distance/time = 3/4*8 = 6 kmph
now, speed in still water = 1/2* (4+6)
= 10/2
= 5 kmph
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