If a fisherman rows upstream at 7kmph, and downstream at 10kmph, what is the speed of the stream?  Choose the correct choice from the following choices:
A) 1.7 kmph	B) 1.5 kmph	C) 2.5 kmph	D) 1.9 kmph	E) 3.5 kmph
Sol.   Speed of stream = 1/2(10 -7) kmph = 1.5 kmph.   Answer 1.5 kmph
<result>B</result>
If a fisherman rows upstream at 7kmph, and downstream at 10kmph, what is the speed of the stream?