Question 468359
d = rt
t = d/r
2 = d/2 + d/8 = 5d/8
5d = 16
d = 3.2 miles one way
--> 6.4 miles total
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Another approach:
The average speed of a round trip is
2*v1*v2/(v1 + v2)
2*2*8/(2+8) = 3.2 mph
It's similar to parallel resistors, but 2 times that.
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His avg speed was 3.2 mph for 2 hours = 6.4 miles round trip