SOLUTION: Tyra averages 40 mi/her driving to the airport during rush hour and 60mi/he on the return trip late at night. What is Tyra's average speed for the entire trip?

Question 1011283: Tyra averages 40 mi/her driving to the airport during rush hour and 60mi/he on the return trip late at night. What is Tyra's average speed for the entire trip?
Found 2 solutions by josmiceli, solver91311:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Average speed is always:
[ total distance traveled ] / [ total traveling time ]
Let = one-way distance to airport
---------------------
Time for trip to airport:

Time for trip back from airport:

--------------------------
The average speed is:

Divide top and bottom by

Multiply top and bottom by

Her average speed is 48 mi/hr for the whole trip
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!

The average rate of speed for an entire trip is the total distance travelled divided by the total travel time. Since neither the distance or total time was given, I have to assume that whoever wrote the problem intended for you to assume that she drove to the airport during rush hour and then when she arrived it was instantaneously late at night and she immediately turned around and drove home, which is to say there was no delay or wait time at the airport. Without this assumption, this problem cannot be solved as presented. You might want to point out to your instructor that story problems are much more instructive if the story actually makes sense in the real world.

The amount of time, , it takes to go miles at is , and the amount of time, , it takes to go miles at is . This is based on the fact that the distance to the airport is assumed to be the same as the distance home from the airport. Then we can say that the total time, , is:

Add the two fractions by finding the common denominator:

but the total distance traveled is , so:

or

And the average speed is then

John

My calculator said it, I believe it, that settles it

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