Question 577792
 if your on a plane that went 480 miles... and for the first 240 miles you went 60 and the last 240 you did 50mph what was your average mph for the trip

i took the two mph and dived by 2 to get 55
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Avg = 2*60*50/(60+50) = 6000/110
=~ 54.55 mi/hr
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It's not the average of 50 & 60
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Find the total time:
t = 240/60 + 240/50 = 4 + 24/5
t = 44/5 hours
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r = d/t = 480/(44/5) = 2400/44
= same answer
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It's not the avg of 60 & 50 because more time is spent moving at the lower speed.
If the 2 speeds were 60 & 30, the overall speed = 40, not 45.
This applies to round-trips, or trips of equal distance only.