Aptitude Hack#90(24-5-19)

Question:

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?

   A )   6km
   B )   5km
   C )   8km
   D )   3km

Answer : D) 3km

Explaination : 

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.