A boat running downstream covers a distance of 20 km in 2 hours while for covering the same distance upstream, it takes 5 hours. What is the speed of the boat in still water?	Choose the correct choice:
A) 6	B) 7	C) 8	D) 9	E) 1
Explanation:   Rate downstream = (20/2)= 
<gadget id="calculator">(20/2)</gadget>
<output>10</output>
10 kmph;   Rate upstream= (20/5)= 
<gadget id="calculator">(20/5)</gadget>
<output>4</output>
4 kmph   Speed in still water= 1/2 (10 + 4) kmph = 7 kmph   ANSWER: 7
<result>B</result>
A boat running downstream covers a distance of 20 km in 2 hours while for covering the same distance upstream, it takes 5 hours. What is the speed of the boat in still water?