SOLUTION: Going from point A to point B a driver averages 60mph. On the return trip along the same route he averages 40mph. What is the average rate for the entire trip?

Question 383994: Going from point A to point B a driver averages 60mph. On the return trip along the same route he averages 40mph. What is the average rate for the entire trip?
Found 2 solutions by mananth, Alan3354:
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
A to B = 60 mph
B to A = 40 mph
..
lets be practical
while going to B
speed = 40 mph
Assume it takes 1 hour
so distance = 40 miles
..
while returning the speed = 60 mph
distance = 40
time= 40/60 = 2/3 hours
..
Average speed for the trip = total distance / total time
..
Total distance = 80 miles
total time= 1+2/3 hours
=1 2/3
=5/3 hours
..
80/(5/3)
80*3/5
=16*3
=48 mph is the average speed
..
does your teacher approve of this logic
..
m.ananth@hotmail.ca

Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
It's not 50 mph. More time is spent moving at 40 mph than moving at 60 mph. It's always less than the average of the 2 speeds, unless they're equal.
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d = rt
t = d/r
d = the distance, so t = 2d/r for the round trip
2t = d/60 + d/40 = 100d/2400 = d/24 (total time)
t = d/48
r = 48 mph

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