A boatman can row 3 km against the stream in 36 minutes and return in 18 minutes. Find the rate of current ?
Answers:
A) 7/2 kmph B) 2.5 kmph C) 5/2 kmph D) 1/2 kmph E) 2/2 kmph
Explanation:   Speed in upstream = Distance / Time = 3 x 60/36 = 5 km/hr.   Speed in downstream = 3 x 60/18 = 10 km/hr   Rate of current = (10-5)/2= 
<gadget id="calculator">(10-5)/2</gadget>
<output>5/2 = around 2.5</output>
2.5 km/hr.   Answer: 2.5 kmph
<result>B</result>
A boatman can row 3 km against the stream in 36 minutes and return in 18 minutes. Find the rate of current ?