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San Francisco is approximately 60 miles from San Jose. John’s family travelled from San Francisco to San Jose averaging 40 miles per hour, but on the way back, due to heavy traffic, they only averaged 20 miles per hour. What is the average speed of the entire trip, in miles per hour?

 Jun 3, 2022
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Average speed ==Harmonic mean

 

[2 * 20 * 40] / [20 + 40] ==1,600 / 60 ==26 2/3 mph - average speed.

 

OR:

60 / 40 ==1.5 hours to San Jose

60 / 20 ==3.00 hours to San Francisco

Average speed ==Total distance / total time

Average speed==[60 x 2] / [1.5 + 3] ==120 /4.5==26 2/3 mph 

 Jun 3, 2022

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