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 6 kilometers per hour?
-
A6.75
-
B7
-
C7.25
-
D7.5
-
E7.75
显示答案
正确答案: D