A boat running downstream covers a distance of 24 km in 3 hours while for covering the same distance upstream,it takes 4 hours.What is the speed of the boat in still water ? Choose the correct option:
A) 4 km/hr	B) 6 km/hr	C) 8 km/hr	D) 7 km/hr	E) None of these
Solution   Rate downstream =(24/3)= 
<gadget id="calculator">(24/3)</gadget>
<output>8</output>
8 kmph, Rate upstream=(24/4)= 
<gadget id="calculator">(24/4)</gadget>
<output>6</output>
6 kmph.   ∴ Speed in still water=1/2(8+6) kmph = 7 kmph.   Answer 7 km/hr
<result>D</result>
A boat running downstream covers a distance of 24 km in 3 hours while for covering the same distance upstream,it takes 4 hours.What is the speed of the boat in still water ?