A man goes 6 km against the current of the stream in 3 hr and goes 2 km along the stream in 30 min. How long will it take to go 4 km in stationary water? Choose the most appropriate option.
A) 1 hr 20 min	B) 1 hr 40 min	C) 2 hr 30 min	D) 3 hr 20 min	E) None of these
Explanation:   Speed up stream = 6/3= 
<gadget id="calculator">6/3</gadget>
<output>2</output>
2 km/hr   Speed down stream= 2/(1/2)= 
<gadget id="calculator">2/(1/2)</gadget>
<output>4</output>
4 km/hr   Speed in still water= 1/2(2+4) = 6/2= 
<gadget id="calculator">6/2</gadget>
<output>3</output>
3 km/hr   Time taken to travel 4 km in still water is= 4/3 = 1 (1/3) hr = 1 hr 20 min   1 hr 20 minnswer: Option 1 hr 20 min
<result>A</result>
A man goes 6 km against the current of the stream in 3 hr and goes 2 km along the stream in 30 min. How long will it take to go 4 km in stationary water?