SOLUTION: Peggy drives to town at a rate of 40 km/h. How fast must she drive BACK in order to average 80 km/h for the entire trip?

Algebra.Com
Question 1152453: Peggy drives to town at a rate of 40 km/h. How fast must she drive BACK in order to average 80 km/h for the entire trip?
Found 2 solutions by Alan3354, ikleyn:
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
Peggy drives to town at a rate of 40 km/h. How fast must she drive BACK in order to average 80 km/h for the entire trip?
===========
This is a "trick question."
The time spent going at 40 is the same time as a round trip at 80.
Time is up.
It's not possible.
Answer by ikleyn(52775)   (Show Source): You can put this solution on YOUR website!
.

If one-way distance is "d" kilometers, then one-way time is  hours.


The two-ways distance ("to there" and back) is 2d, and two-ways time is   =  hours.


In other words, at given condition, all the time is spent for one-way distance "to there", and there is NO TIME for the way back.


Therefore, the trip under given condition is IMPOSSIBLE.    ANSWER

------------

Solved, answered and explained. And completed.



RELATED QUESTIONS

Peggy drives to town at a rate of 40 km/h. How fast must she drive in order to average 80 (answered by ikleyn,Alan3354)
two towns are 80 km apart . kasia wants to drive from one town to the other in exactly... (answered by Theo)
A train averaged 80 km/h for the first half of its trip. How fast must it travel for the (answered by josmiceli,jojo14344)
If you drive 2 h at 80 km/h, how fast must you drive during the next hour in order to... (answered by longjonsilver,amalm06)
An automobile travels from point A to point B at a speed of 40 km/h. How fast must it... (answered by malaydassharma)
A train averaged 80 km/h for the first half of its trip. How fast must it travel for the... (answered by solver91311)
In the first half (distance) of a trip, a truck travels at a speed of 40 km/hr. How fast... (answered by ankor@dixie-net.com)
On a 100km track a train travells the first 30km at a uniform speed of 30km/h . How fast... (answered by Fombitz)
Two towns are 80 km. apart. Sylvia wants to drive from one town to the other in exactly... (answered by ptaylor)