Noelle walks from point A to point B at an average speed of 5 kilometers per hour. At what speed, in kilometers per hour, must Noelle walk from point B to point A so that her average speed for the entire trip is 8 kilometers per hour?  Choose the correct choice:
A) 6.75
B) 7
C) 7.25
D) 7.5
E) 20
Let's suppose that speed while returning was xkm/h   Since the distance is same, we can apply the formula of avg speed   Avg speed= 2S1S2/S1+S2   8= 2*5*x/5+x   x= 20   20 is the answer
<result>E</result>
Noelle walks from point A to point B at an average speed of 5 kilometers per hour. At what speed, in kilometers per hour, must Noelle walk from point B to point A so that her average speed for the entire trip is 8 kilometers per hour?