A boat running downstream cover a distance of 16km in 2 hr while covering the same distance upstream it takes 4 hr then the speed of the boat still in the water	Choose the correct choice from the following answers.
A) 43km/hr
B) 78km/hr
C) 9km/hr
D) 7km/hr
E) 3km/hr
rate down stream=(16/2)= 
<gadget id="calculator">(16/2)</gadget>
<output>8</output>
8 kmph   rate upstream=(16/4)= 
<gadget id="calculator">(16/4)</gadget>
<output>4</output>
4 kmph   speed still water=1/2(8+4)kmph=km/hr   Answer(9km/hr)
<result>C</result>
A boat running downstream cover a distance of 16km in 2 hr while covering the same distance upstream it takes 4 hr then the speed of the boat still in the water