A man can row 25/2 km an hour in still water and he finds that it takes him thrice as long to row up as to row down the river. The rate of stream is:
Let the rate of stream be x km/hr Then, Speed of downstream = `(25/2) + x` km/hr Speed of upstream = `(25/2) - x` km/hr (12.5 + x) = 3 (12.5 - x ) 12.5 + x = 37.5 - 3x 4x = 25 x = 6.25 km/hr
Two mutually exclusive events
