A person can row $$7\frac{1}{2}$$ km an hour in still water. Finds that it takes twice the time to row upstream than the time to row downstream. The speed of the stream is:
A. 2 kmph
B. 2.5 kmph
C. 3 kmph
D. 4 kmph
Answer: Option B
Solution(By Examveda Team)
Let the distance covered be x km and speed of stream = y kmph. Speed downstream = $$\frac{{15}}{2} + y$$ kmph Speed upstream = $$\frac{{15}}{2} - y$$ kmph $$\eqalign{ & {\text{According}}\,{\text{to}}\,{\text{question,}} \cr & {\frac{{2x}}{{ { {\frac{{15}}{2}} + y} }}} = {\frac{x}{{ { {\frac{{15}}{2}} - y} }}} \cr & or,\,15 - 2y = {\frac{{15}}{2}} + y \cr & or,3y = 15 - {\frac{{15}}{2}} = \frac{{15}}{2} \cr & or,y = \frac{{15}}{6} = 2.5\,{\text{kmph}} \cr} $$Join The Discussion
Comments ( 1 )
Related Questions on Speed Time and Distance
A. 48 min.
B. 60 min.
C. 42 min.
D. 62 min.
E. 66 min.
A. 262.4 km
B. 260 km
C. 283.33 km
D. 275 km
E. None of these
A. 4 hours
B. 4 hours 30 min.
C. 4 hours 45 min.
D. 5 hours
15/2+y = 2(15/2-y)
So y = 2.5