In a river flowing at 2 km/hr, a boat travels 64 km upstream and then returns downstream to the starting point. If its speed in still water be 6 km/hr, find the total journey time.  Select:
A) 10 hours
B) 12 hours
C) 14 hours
D) 24 hours
E) None of these
Explanation :   speed of the boat = 6 km/hr   Speed downstream = (6+2)= 
<gadget id="calculator">(6+2)</gadget>
<output>8</output>
8 km/hr   Speed upstream= (6-2)= 
<gadget id="calculator">(6-2)</gadget>
<output>4</output>
4 km/hr   Distance travelled downstream= Distance travelled upstream = 64 km   Total time taken = Time taken downstream + Time taken upstream   = (64/8) + (64/4) = = 24 hr. Answer : Option 24 hours
<result>D</result>
In a river flowing at 2 km/hr, a boat travels 64 km upstream and then returns downstream to the starting point. If its speed in still water be 6 km/hr, find the total journey time.