SOLUTION: a student bikes to school averaging 5 mph. he bikes home the exact same distance averaging 10 mph. what is his average speed for the round trip?

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: a student bikes to school averaging 5 mph. he bikes home the exact same distance averaging 10 mph. what is his average speed for the round trip?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 854941: a student bikes to school averaging 5 mph. he bikes home the exact same distance averaging 10 mph. what is his average speed for the round trip?
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
If the school was 10 miles from the student's home,
it would take him 10miles%2F5mph=2hours to bike to school,
and 10miles%2F10mph=1hours to bike home.
The round trip would be 2%2A10miles=20miles
and it would take 2hours%2B1hour=3hours .
the average speed would be
20miles%2F3hours=highlight%286.3mph%29 (rounded).

The 10 mile distance was made up, but the calculation would be the same with any distance.
We could say, it is d miles,
so the times in hours would be d%2F5 and d%2F10.
The round trip would be 2d miles,
and it would take d%2F5%2Bd%2F10=2d%2F10%2Bd%2F10=3d%2F10 hours.
Them, the speed (in mph) would be calculated as
2d%2F%283d%2F10%29=2d%2A%2810%2F3d%29=20d%2F30d=20%2F3=6.3 .
The distance cancels out, and it was easier to understand and calculate by making d=10miles .