<PRE><B>Question 188738</B>
A worker drove to work traveling 65 miles per hour. He returned home traveling 55 miles per hour. What was his average speed if the entire trip took 4 hours?
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d = rt
t = d/r
4 = d/55 + d/65
4 = (13d + 11d)/715
24d = 2860
d = 119 1/6 miles each way
r (avg) = 2d/4
r = 59 5/6 mph</PRE>