A man can row upstream at 10kmph and downstream at 18 kmph. The speed of the stream is Choose the correct option:
A) 2.5 km/hr
B) 4 km/hr
C) 5 km/hr
D) 10.5 km/hr
E) None
Sol.   Speed of stream = 1/2(18 -10) kmph = 4 kmph.   Answer 4 km/hr
<result>B</result>
A man can row upstream at 10kmph and downstream at 18 kmph. The speed of the stream is