A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr. find the time taken by the boat to go 72 km downstream?	Choices:
A) 2 hours
B) 4 hours 12 minutes
C) 4 hours
D) 5 hours
E) None
Solution   Speed Downstream	= (13 + 4) km/hr   = 17 km/hr.   Time taken to travel 72 km downstream	=(72 / 17)hrs   = 4 hrs 12 minutes.   Answer 4 hours 12 minutes
<result>B</result>
A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr. find the time taken by the boat to go 72 km downstream?