SOLUTION: if ben drives on a highway 80 miles 30 mi/hr. then back on the same highway, but 40 mi/hr. what is his average rate

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: if ben drives on a highway 80 miles 30 mi/hr. then back on the same highway, but 40 mi/hr. what is his average rate      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 811533: if ben drives on a highway 80 miles 30 mi/hr. then back on the same highway, but 40 mi/hr. what is his average rate
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
if ben drives on a highway 80 miles 30 mi/hr. then back on the same highway, but 40 mi/hr. what is his average rate
-------------
RT time = 80/30 + 80/40 hours
------
Avg rate = 160/(RT time)
----
If you work that out, you'll find that
avg rate = 2*30*40/(30 + 40)
= 240/7 mi/hr
=~ 34.71 mi/hr
This is true regardless of the distance.