amy wants to travel from elmtown to lakeside at an average speed of 50 miles/hour. she travels half the distance and discovers that her average speed has been only 25 miles/hour. how fast must she drive for the remaining part of the trip if she is to average 50 miles per hour for the entire trip?

Answer 1

she has gone half the distance at half of her desired speed

she has used up all the time needed for her desired trip

she needs to be at lakeside NOW ... magic maybe?

Answer 2

(25 + (50+x))/2 = 50.
(75 + x)/2 = 50,
75+x = 100,
X = 25 mi/h.

50 + x = 50 + 25 = 75 mi/h during 2nd half of trip.