A boat sails 15 km of a river towards upstream in 5 hours. How long will it take to cover the same distance downstream, if the speed of current is one-fourth the speed of the boat in still water:	Options:
A) 2
B) 3
C) 4
D) 5
E) 6
Explanation:   Upstream speed = 3-S   Downstream speed = 3+s   3-S = 15/5= 
<gadget id="calculator">15/5</gadget>
<output>3</output>
3 km/h   Again 3= 4S   Therefore 3-S = 3= 3S   =&gt; S = 1 and 3= 4 km/h   Therefore 3+S = 5km/h   Therefore, Time during downstream = 15/5= 
<gadget id="calculator">15/5</gadget>
<output>3</output>
3h   Answer: 3) 3h
<result>B</result>
A boat sails 15 km of a river towards upstream in 5 hours. How long will it take to cover the same distance downstream, if the speed of current is one-fourth the speed of the boat in still water: