26.
A man rows 750 m in 675 seconds against the stream and returns in 7 and half
minutes. His rowing speed in still water is: . [Assistant Grade]
3
km/hr 5 km/hr
4
km/hr 6 km/hr
Answer: 5 km/hr
Explanation: Rate upstream = (750/675) = 10/9
m/sec
Rate
downstream (750/450) m/sec = 5/3 m/sec.
Rate
in still water = (1/2)*[(10/9) + (5/3)] m/sec. = 25/18 m/sec
=
(25/18)*(18/5) kmPh = 5 kmph
