timmaxwell8 wrote:

A cyclist bikes x distance at 10 miles per hour and returns over the same path at 8 miles per hour. What is the cyclist's average rate for the round trip in miles per hour?

A. 8.1

B. 8.3

C. 8.6

D. 8.9

E. 9.0

This is clearly a round trip question so we should consider the formula

Total Distance= AvgSpeed * Time Spent

And also that

Distance1= Distance2 (we hold the distance constant because of course the distance on each trip is obviously the same)

Now we can just plug in a simple value

40/8 = 5 hours

40/10= 4 hours

80miles= Avgspeed * 9 hours

80/9= 8.888888 so round up

D