A boatman can row 3 km against the stream in 20 minutes and return in 9 minutes. Find the rate of current ?	Select.
A) 7/2 kmph  B) 8/2 kmph  C) 5.5 kmph  D) 1/2 kmph  E) 2/2 kmph
Explanation:   Speed in upstream = Distance / Time = 3 x 60/20 = 9 km/hr.   Speed in downstream = 3 x 60/9 = 20 km/hr   Rate of current = (20-9)/2= 
<gadget id="calculator">(20-9)/2</gadget>
<output>11/2 = around 5.5</output>
5.5 km/hr.   Answer: 5.5 kmph
<result>C</result>
A boatman can row 3 km against the stream in 20 minutes and return in 9 minutes. Find the rate of current ?