A boatman goes 2 km against the current of the stream in 1 h and goes 1 km along the current in 10 min. How long will it take to go 5 km in stationary water? |
A) 80 min
B) 75 min
C) 70 min
D) 72 min
E) 84 min
Correct Answer: B
Solution :
Upstream speed = 2 km/h |
Downstream speed \[=\frac{1}{10}=6\,km/h\] |
\[\therefore \] Speed in still water \[=\frac{2+6}{2}=4\,km/h\] |
Time required to go 5 km in still water |
\[=\frac{5}{4}h=1\,h\,15\,\min =75\min \] |
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