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A boat moves with speed of 5 km/h relati...

A boat moves with speed of 5 km/h relative to water in a river flowing with a speed of 3 km/h and having a width of 1 km. The minimum time taken around a round trip is

A

5 min

B

60 min

C

20 min

D

30 min

Text Solution

Verified by Experts

The correct Answer is:
D
For the round trip he should cross perpendicular to the river
`because` time for trip to that side `=(1km)/(4(km)/(hr))=0.25`hr
To come back, again he takes 0.25hr to cross the river. Total time is 30 min, he goes to the other bank and comes back at the same point.
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