Noelle walks from point A to point B at an average speed of 3 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 4 kilometers per hour? Choose the correct answer
A) 5.75  B) 6  C) 7.25  D) 7.5  E) 7.75
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   4= 2*3*x/3+x   x= 6   6 is the answer
<result>B</result>
Noelle walks from point A to point B at an average speed of 3 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 4 kilometers per hour?