A boatman goes 4 km against the current of the stream in 4 hour and goes 1 km along the current in 20 minutes. How long will it take to go 6 km in stationary water?  Choose the correct option:
A) 5 hours	B) 1 hours	C) 3 hours	D) 2 hours	E) 4 hours
Speed upstream =4/4= 
<gadget id="calculator">4/4</gadget>
<output>1</output>
1 km/hr   Speed downstream= 1/(20/60)= 
<gadget id="calculator">1/(20/60)</gadget>
<output>3</output>
3 km/hr   Speed in still water= 1/2(3+1)=2 km/hr   Time taken to travel 6 km in still water =6/2= 
<gadget id="calculator">6/2</gadget>
<output>3</output>
3 hours   ANSWER:3 hours
<result>C</result>
A boatman goes 4 km against the current of the stream in 4 hour and goes 1 km along the current in 20 minutes. How long will it take to go 6 km in stationary water?