Discussion :: Boats and Streams
-
A man can row three-quarters of a kilometre against the stream in 11 minutes and down the stream in 7 minutes. The speed (in km/hr) of the man in still water is:
Answer : Option D
Explanation :
We can write three-quarters of a kilometre as 750 metres,
and 11 minutes as 675 seconds.
Rate upstream=\([ \frac { 750 } { 675 }]m/sec\)=\(\frac { 10 } { 9 }m/sec\)
Rate downstream =\([ \frac { 750 } { 450 }]m/sec\)=\(\frac { 5 } {3}m/sec\)
=\(\frac { 25 } {18}m/sec\)
=[\(\frac { 25 } {18}*\)\(\frac {18} {5}\)]km/hr
= 5 km/hr.
Be The First To Comment