The speed of a motor-boat is that of the current of water as 36:5. The boat goes along with the current in 5 hours 10 minutes. It will come back in:
A. 5 hours 50 minutes
B. 6 hours
C. 6 hours 50 minutes
D. 12 hours 10 minutes
Answer: Option C
Solution(By Examveda Team)
Let the speed of the motor boat = 36x kmph and speed of current = 5x kmph.The boat goes along with the current in 5 hours 10 minutes = $$\frac{{31}}{6}$$ hour $$\eqalign{ & {\text{Hence, Distance}} \cr & = {\frac{{31}}{6}} \times \left( {36x + 5x} \right) \cr & = \frac{{41x + 31}}{6}\,km \cr & {\text{Speed of boat upstream}} \cr & = 36x + 5x = 31x\,{\text{kmph}} \cr & {\text{Hence, time taken to come back}} \cr & = {\frac{{ {41x \times {\frac{{31}}{6}} } }}{{31x}}} \cr & = \frac{{41}}{6}\,{\text{hours}} \cr & = 6\,{\text{hours}}\,\,50\,{\text{minutes}} \cr} $$
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Comments ( 2 )
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
Md Doud
D=st
t=D/s
where, D=(41x+31)/6
Hence time taken to came back,, after the equation is not undersatnable. Please someone make it clear.