A man can row 7 ½ kmph in still water. If in a river running at 1.5 km/hr an hour, it takes him 50 minutes to row to a place and back, how far off is the place?

Question

A. 2 km

B. 3 km

C. 4km

D. 5km

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Correct Answer :

B. 3 km

Speed downstream =(7.5+1.5)km/hr=9 km/hr;

Speed upstream=(7.5-1.5)kmph=6kmph.

Let the required distance be x km.then,

x/9+x/6=50/60.

2x+3x=(5/6*18)

5x=15

x=3.

Hence, the required distance is 3km.

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