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40 votes
40 votes
A motorist travels 90 miles at a rate of 20 miles per hour. If he returns the same distance at a rate of 40 miles per hour, what is the average speed for the entire trip, in miles per hour? (Explain)

User Partho
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1 Answer

25 votes
25 votes

Answer:

26 2/3

Explanation:

Average speed is total distance divided by total time.

The time for the first trip was ...

(90 mi)/(20 mi/h) = 4.5 h

The time for the return trip was ...

(90 mi)/(40 mi/h) = 2.25 h

Then the average for the trip and return is ...

total miles/total time = (90 +90)/(4.5 +2.25) = 26 2/3 . . . . mi/h

The average speed for the round trip was 26 2/3 miles per hour.

User Ulkas
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