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