Question
A man rows upstream 36 km and downstream 51 km taking 3
hours each. Find the man’s speed in still water.    ÂSolution
Distance upstream= 36 km, time taken to row upstream = 3 hrs. 
 Speed upstream = `36/3`  =12 km/hr. Distance downstream= 51 km, time taken to row downstream = 3 hrs.  Speed downstream = `51/3`  = 17 km/hr. 
 Man’s rate in still water = `1/2`  (17+12) kmph = 14.5 kmph    Â
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