A boatman goes 3 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water? Choose the correct answer:
A) 40 minutes
B) 1 hour 7 min
C) 1 hour 15 min
D) 1 hour 30 min
E) 1 hour 10 min
speed (upstream) =3/1= 
<gadget id="calculator">3/1</gadget>
<output>3</output>
3 kmhr   speed (downstream)=1/(10/60)= 
<gadget id="calculator">1/(10/60)</gadget>
<output>6</output>
6 kmhr   speed in still water= 1/2 (3+6) = 4.5 kmhr   time taken in stationary = 5/4.5 = 1 hrs 7 min   ANSWER:1 hour 7 min
<result>B</result>
A boatman goes 3 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water?